feat: generalize Settings 'Power Genius' into 'Amplifier' (type + serial/IP transport) for SPE Expert

Renames the Hardware section to Amplifier and adds an amplifier-type selector
(4O3A PowerGenius XL, SPE Expert 1.3K-FA / 1.5K-FA / 2K-FA) plus a transport
choice for the SPE amps: USB (serial COM + baud) or Network (RS232-to-Ethernet
IP:port). PGXLSettings gains Type/Transport/ComPort/Baud (keys keep the pgxl.*
prefix for back-compat). PowerGenius still drives over TCP; SPE settings are
stored but control is not wired yet (needs the SPE serial protocol).

app.go

@@ -182,10 +182,16 @@ const (
 	keyAntGeniusHost     = "antgenius.host"
 	keyAntGeniusPassword = "antgenius.password" // remote/AUTH password (blank on LAN)
 
-	// PowerGenius XL (4O3A) amplifier fan-mode control — Hardware → PowerGenius.
-	keyPGXLEnabled = "pgxl.enabled"
-	keyPGXLHost    = "pgxl.host"
-	keyPGXLPort    = "pgxl.port"
+	// Amplifier control — Hardware → Amplifier (PowerGenius XL over TCP; SPE Expert
+	// over USB serial or an RS232-to-Ethernet bridge). Keys keep the pgxl.* prefix
+	// for backward compatibility with existing saved settings.
+	keyPGXLEnabled   = "pgxl.enabled"
+	keyPGXLHost      = "pgxl.host"
+	keyPGXLPort      = "pgxl.port"
+	keyPGXLType      = "pgxl.type"      // "pgxl" | "spe13" | "spe15" | "spe2k"
+	keyPGXLTransport = "pgxl.transport" // "tcp" | "serial"
+	keyPGXLComPort   = "pgxl.com_port"
+	keyPGXLBaud      = "pgxl.baud"
 
 	// WinKeyer CW keyer (serial) — Hardware → CW Keyer.
 	keyWKEnabled    = "winkeyer.enabled"
@@ -11397,28 +11403,58 @@ func boolStr(b bool) string {
 // StationDevice is one configured relay board for the Station Control tab.
 type StationDevice struct {
 	ID     string   `json:"id"`
-	Type   string   `json:"type"` // "webswitch" | "kmtronic"
+	Type   string   `json:"type"` // "webswitch" | "kmtronic" | "denkovi" | "usbrelay"
 	Name   string   `json:"name"`
-	Host   string   `json:"host"`
+	Host   string   `json:"host"` // IP for network boards; FTDI serial for denkovi; COM port for usbrelay
 	User   string   `json:"user,omitempty"` // KMTronic HTTP auth (blank = none)
 	Pass   string   `json:"pass,omitempty"`
+	Channels int    `json:"channels,omitempty"` // usbrelay only: number of relays (1/2/4/8/16)
 	Labels []string `json:"labels"` // per-relay label (index 0 = relay 1)
 }
 
+// deviceRelayCount is the relay count for a configured device — fixed by type,
+// except the Denkovi (4 or 8) and the generic USB-serial board, whose channel
+// count the user picks.
+func deviceRelayCount(d StationDevice) int {
+	if d.Type == "usbrelay" || d.Type == "denkovi" {
+		if d.Channels >= 1 {
+			return d.Channels
+		}
+		return 8
+	}
+	return relayCountFor(d.Type)
+}
+
 // relayCountFor returns a device type's fixed relay count.
 func relayCountFor(typ string) int {
-	if typ == "kmtronic" {
+	switch typ {
+	case "kmtronic", "denkovi":
 		return 8
+	default:
+		return 5 // webswitch 1216H
 	}
-	return 5 // webswitch 1216H
 }
 
 // deviceDriver builds the wire driver for a configured device.
 func deviceDriver(d StationDevice) relaydev.Device {
-	if d.Type == "kmtronic" {
+	switch d.Type {
+	case "kmtronic":
 		return relaydev.NewKMTronic(d.Host, d.User, d.Pass)
+	case "denkovi":
+		// Host carries the FTDI serial number (e.g. "DAE0006K"), not a hostname.
+		return relaydev.NewDenkovi(d.Host, deviceRelayCount(d))
+	case "usbrelay":
+		// Host carries the COM port (e.g. "COM5"); CH340/LCUS "A0" serial protocol.
+		return relaydev.NewSerialRelay(d.Host, deviceRelayCount(d))
+	default:
+		return relaydev.NewWebswitch(d.Host)
 	}
-	return relaydev.NewWebswitch(d.Host)
+}
+
+// ListDenkoviDevices returns the FTDI serial numbers of connected Denkovi/FTDI
+// boards, for the settings picker. Windows-only (FTDI D2XX).
+func (a *App) ListDenkoviDevices() ([]string, error) {
+	return relaydev.ListDenkovi()
 }
 
 // GetStationDevices returns the configured relay boards (without live state).
@@ -11444,13 +11480,16 @@ func (a *App) SaveStationDevices(devs []StationDevice) error {
 		return fmt.Errorf("db not initialized")
 	}
 	for i := range devs {
-		if devs[i].Type != "kmtronic" {
+		switch devs[i].Type {
+		case "kmtronic", "denkovi", "usbrelay", "webswitch":
+			// known type — keep
+		default:
 			devs[i].Type = "webswitch"
 		}
 		if strings.TrimSpace(devs[i].ID) == "" {
 			devs[i].ID = fmt.Sprintf("dev%d-%d", i, time.Now().UnixNano())
 		}
-		n := relayCountFor(devs[i].Type)
+		n := deviceRelayCount(devs[i])
 		for len(devs[i].Labels) < n {
 			devs[i].Labels = append(devs[i].Labels, "")
 		}
@@ -11491,7 +11530,7 @@ func (a *App) GetStationStatus() []StationDeviceStatus {
 		go func(i int) {
 			defer wg.Done()
 			d := devs[i]
-			n := relayCountFor(d.Type)
+			n := deviceRelayCount(d)
 			ds := StationDeviceStatus{ID: d.ID, Name: d.Name, Type: d.Type}
 			ctx, cancel := context.WithTimeout(a.ctx, 6*time.Second)
 			defer cancel()
@@ -12098,19 +12137,25 @@ func (a *App) AntGeniusDeselect(port int) error {
 
 // ── PowerGenius XL (4O3A) amplifier fan control (TCP, default port 9008) ─────
 
-// PGXLSettings is the JSON shape for the Hardware → PowerGenius panel.
+// PGXLSettings is the JSON shape for the Hardware → Amplifier panel. It covers
+// the 4O3A PowerGenius XL (TCP) and the SPE Expert amps (USB serial or an
+// RS232-to-Ethernet bridge). The type name is kept for binding compatibility.
 type PGXLSettings struct {
-	Enabled bool   `json:"enabled"`
-	Host    string `json:"host"`
-	Port    int    `json:"port"`
+	Enabled   bool   `json:"enabled"`
+	Type      string `json:"type"`      // "pgxl" | "spe13" | "spe15" | "spe2k"
+	Transport string `json:"transport"` // "tcp" | "serial"
+	Host      string `json:"host"`      // TCP transport
+	Port      int    `json:"port"`      // TCP transport
+	ComPort   string `json:"com_port"`  // serial transport
+	Baud      int    `json:"baud"`      // serial transport
 }
 
 func (a *App) GetPGXLSettings() (PGXLSettings, error) {
-	out := PGXLSettings{Port: 9008}
+	out := PGXLSettings{Type: "pgxl", Transport: "tcp", Port: 9008, Baud: 115200}
 	if a.settings == nil {
 		return out, fmt.Errorf("db not initialized")
 	}
-	m, err := a.settings.GetMany(a.ctx, keyPGXLEnabled, keyPGXLHost, keyPGXLPort)
+	m, err := a.settings.GetMany(a.ctx, keyPGXLEnabled, keyPGXLHost, keyPGXLPort, keyPGXLType, keyPGXLTransport, keyPGXLComPort, keyPGXLBaud)
 	if err != nil {
 		return out, err
 	}
@@ -12119,6 +12164,16 @@ func (a *App) GetPGXLSettings() (PGXLSettings, error) {
 	if p, _ := strconv.Atoi(m[keyPGXLPort]); p > 0 && p <= 65535 {
 		out.Port = p
 	}
+	if t := strings.TrimSpace(m[keyPGXLType]); t != "" {
+		out.Type = t
+	}
+	if tr := strings.TrimSpace(m[keyPGXLTransport]); tr != "" {
+		out.Transport = tr
+	}
+	out.ComPort = m[keyPGXLComPort]
+	if b, _ := strconv.Atoi(m[keyPGXLBaud]); b > 0 {
+		out.Baud = b
+	}
 	return out, nil
 }
 
@@ -12129,10 +12184,23 @@ func (a *App) SavePGXLSettings(s PGXLSettings) error {
 	if s.Port <= 0 || s.Port > 65535 {
 		s.Port = 9008
 	}
+	if s.Baud <= 0 {
+		s.Baud = 115200
+	}
+	if s.Type == "" {
+		s.Type = "pgxl"
+	}
+	if s.Transport == "" {
+		s.Transport = "tcp"
+	}
 	for k, v := range map[string]string{
-		keyPGXLEnabled: boolStr(s.Enabled),
-		keyPGXLHost:    strings.TrimSpace(s.Host),
-		keyPGXLPort:    strconv.Itoa(s.Port),
+		keyPGXLEnabled:   boolStr(s.Enabled),
+		keyPGXLHost:      strings.TrimSpace(s.Host),
+		keyPGXLPort:      strconv.Itoa(s.Port),
+		keyPGXLType:      s.Type,
+		keyPGXLTransport: s.Transport,
+		keyPGXLComPort:   strings.TrimSpace(s.ComPort),
+		keyPGXLBaud:      strconv.Itoa(s.Baud),
 	} {
 		if err := a.settings.Set(a.ctx, k, v); err != nil {
 			return err
@@ -12152,7 +12220,17 @@ func (a *App) startPGXL() {
 		a.pgxl = nil
 	}
 	s, err := a.GetPGXLSettings()
-	if err != nil || !s.Enabled || strings.TrimSpace(s.Host) == "" {
+	if err != nil || !s.Enabled {
+		return
+	}
+	// Only the PowerGenius XL (TCP) is driven for now. SPE Expert control (serial /
+	// RS232-to-Ethernet) is a separate protocol, not yet implemented — its settings
+	// are stored but no client is started.
+	if s.Type != "" && s.Type != "pgxl" {
+		applog.Printf("amplifier: type %q selected — control not implemented yet (settings saved)", s.Type)
+		return
+	}
+	if strings.TrimSpace(s.Host) == "" {
 		return
 	}
 	a.pgxl = powergenius.New(s.Host, s.Port)

frontend/src/components/SettingsModal.tsx

@@ -276,7 +276,7 @@ const SECTION_LABELS: Partial<Record<SectionId, string>> = {
   winkeyer: 'CW Keyer',
   antenna: 'Ultrabeam / Steppir',
   antgenius: 'Antenna Genius',
-  pgxl: 'Power Genius',
+  pgxl: 'Amplifier',
   flex: 'FlexRadio',
   relayauto: 'Relay auto-control',
   audio: 'Audio devices',
@@ -647,7 +647,7 @@ function ADIFMonitorPanel() {
 type RelayRuleUI = { device_id: string; relay: number; mode: string; freq_lo_khz: number; freq_hi_khz: number; bands: string[] };
 type StationDevUI = { id: string; type: string; name: string; labels: string[] };
 const RELAY_BANDS = ['160m', '80m', '60m', '40m', '30m', '20m', '17m', '15m', '12m', '10m', '6m', '4m', '2m', '70cm'];
-const relayCountUI = (type: string) => (type === 'kmtronic' ? 8 : 5);
+const relayCountUI = (type: string) => (type === 'kmtronic' || type === 'denkovi' ? 8 : 5);
 function RelayAutoPanel() {
   const { t } = useI18n();
   const [enabled, setEnabled] = useState(false);
@@ -698,7 +698,7 @@ function RelayAutoPanel() {
         <div key={dev.id} className="rounded-md border border-border">
           <div className="px-3 py-1.5 border-b border-border bg-muted/40 text-xs font-semibold">{dev.name || dev.id}</div>
           <div className="divide-y divide-border/60">
-            {Array.from({ length: relayCountUI(dev.type) }, (_, i) => i + 1).map((relay) => {
+            {Array.from({ length: (dev.labels?.length || relayCountUI(dev.type)) }, (_, i) => i + 1).map((relay) => {
               const r = ruleFor(dev.id, relay);
               const label = (dev.labels?.[relay - 1] || '').trim() || `${t('relayauto.relay')} ${relay}`;
               return (
@@ -1013,8 +1013,9 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
   // Antenna Genius (4O3A) switch settings — TCP port is fixed at 9007.
   const [antgenius, setAntgenius] = useState<{ enabled: boolean; host: string; password: string }>({ enabled: false, host: '', password: '' });
 
-  // PowerGenius XL (4O3A) amp fan-control settings.
-  const [pgxl, setPgxl] = useState<{ enabled: boolean; host: string; port: number }>({ enabled: false, host: '', port: 9008 });
+  // Amplifier control settings (PowerGenius XL over TCP; SPE Expert over serial/IP).
+  const [pgxl, setPgxl] = useState<{ enabled: boolean; type: string; transport: string; host: string; port: number; com_port: string; baud: number }>(
+    { enabled: false, type: 'pgxl', transport: 'tcp', host: '', port: 9008, com_port: '', baud: 115200 });
 
   // WinKeyer CW keyer settings + macro editor.
   type WKMac = { label: string; text: string };
@@ -2645,36 +2646,89 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
   }
 
   function PGXLPanelSettings() {
+    const isPGXL = pgxl.type === 'pgxl';
+    const isSerial = pgxl.transport === 'serial';
     return (
       <>
-        <SectionHeader
-          title="Power Genius XL"
-        />
+        <SectionHeader title="Amplifier" />
         <div className="space-y-4 max-w-xl">
           <label className="flex items-center gap-2 text-sm cursor-pointer">
             <Checkbox checked={pgxl.enabled} onCheckedChange={(c) => setPgxl((s) => ({ ...s, enabled: !!c }))} />
-            Enable PowerGenius fan control
+            Enable amplifier control
           </label>
-          <div className="grid grid-cols-3 gap-3">
-            <div className="space-y-1 col-span-2">
-              <Label>Host / IP</Label>
-              <Input
-                value={pgxl.host ?? ''}
-                onChange={(e) => setPgxl((s) => ({ ...s, host: e.target.value }))}
-                placeholder="192.168.1.70"
-                className="font-mono"
-              />
-            </div>
+
+          <div className="grid grid-cols-2 gap-3">
             <div className="space-y-1">
-              <Label>TCP port</Label>
-              <Input
-                type="number" min={1} max={65535}
-                value={pgxl.port}
-                onChange={(e) => setPgxl((s) => ({ ...s, port: parseInt(e.target.value) || 9008 }))}
-                className="font-mono"
-              />
+              <Label>Amplifier</Label>
+              <Select value={pgxl.type} onValueChange={(v) => setPgxl((s) => ({ ...s, type: v, transport: v === 'pgxl' ? 'tcp' : s.transport }))}>
+                <SelectTrigger className="h-9"><SelectValue /></SelectTrigger>
+                <SelectContent>
+                  <SelectItem value="pgxl">4O3A PowerGenius XL</SelectItem>
+                  <SelectItem value="spe13">SPE Expert 1.3K-FA</SelectItem>
+                  <SelectItem value="spe15">SPE Expert 1.5K-FA</SelectItem>
+                  <SelectItem value="spe2k">SPE Expert 2K-FA</SelectItem>
+                </SelectContent>
+              </Select>
             </div>
+            {/* PowerGenius is TCP-only; SPE amps connect over USB serial or an
+                RS232-to-Ethernet bridge, so they offer both. */}
+            {!isPGXL && (
+              <div className="space-y-1">
+                <Label>Connection</Label>
+                <Select value={pgxl.transport} onValueChange={(v) => setPgxl((s) => ({ ...s, transport: v }))}>
+                  <SelectTrigger className="h-9"><SelectValue /></SelectTrigger>
+                  <SelectContent>
+                    <SelectItem value="serial">USB (serial COM)</SelectItem>
+                    <SelectItem value="tcp">Network (RS232-to-Ethernet)</SelectItem>
+                  </SelectContent>
+                </Select>
+              </div>
+            )}
           </div>
+
+          {isSerial ? (
+            <div className="grid grid-cols-3 gap-3">
+              <div className="space-y-1 col-span-2">
+                <Label>COM port</Label>
+                <div className="flex items-center gap-2">
+                  <Select value={pgxl.com_port || '_'} onValueChange={(v) => setPgxl((s) => ({ ...s, com_port: v === '_' ? '' : v }))}>
+                    <SelectTrigger className="h-9 flex-1"><SelectValue placeholder="— COM —" /></SelectTrigger>
+                    <SelectContent>
+                      {wkPorts.length === 0 && <SelectItem value="_" disabled>No ports found</SelectItem>}
+                      {wkPorts.map((p) => <SelectItem key={p} value={p}>{p}</SelectItem>)}
+                    </SelectContent>
+                  </Select>
+                  <Button size="sm" variant="outline" className="h-9" onClick={() => ListSerialPorts().then((p) => setWkPorts((p ?? []) as string[])).catch(() => {})}>
+                    <ArrowDown className="size-3.5 rotate-90" />
+                  </Button>
+                </div>
+              </div>
+              <div className="space-y-1">
+                <Label>Baud</Label>
+                <Input type="number" min={1200} value={pgxl.baud}
+                  onChange={(e) => setPgxl((s) => ({ ...s, baud: parseInt(e.target.value) || 115200 }))} className="font-mono" />
+              </div>
+            </div>
+          ) : (
+            <div className="grid grid-cols-3 gap-3">
+              <div className="space-y-1 col-span-2">
+                <Label>Host / IP</Label>
+                <Input value={pgxl.host ?? ''} onChange={(e) => setPgxl((s) => ({ ...s, host: e.target.value }))}
+                  placeholder="192.168.1.70" className="font-mono" />
+              </div>
+              <div className="space-y-1">
+                <Label>TCP port</Label>
+                <Input type="number" min={1} max={65535} value={pgxl.port}
+                  onChange={(e) => setPgxl((s) => ({ ...s, port: parseInt(e.target.value) || 9008 }))} className="font-mono" />
+              </div>
+            </div>
+          )}
+
+          {!isPGXL && (
+            <p className="text-xs text-warning">
+              SPE Expert control is not wired up yet — these settings are saved, but OpsLog can't command the amp until its serial protocol is implemented.
+            </p>
+          )}
         </div>
       </>
     );

frontend/src/components/StationControlPanel.tsx

@@ -12,16 +12,22 @@ import {
   GetStationDevices, SaveStationDevices, GetStationStatus, StationSetRelay,
   GetRotatorHeading, RotatorGoTo, RotatorStop,
   GetUltrabeamStatus, SetUltrabeamDirection, UltrabeamRetract, MotorSetElement, MotorReadElements,
+  ListDenkoviDevices, ListSerialPorts,
 } from '../../wailsjs/go/main/App';
 
 type RotatorProps = { centerLat?: number | null; centerLon?: number | null; bearing?: number | null };
 
-type Device = { id: string; type: string; name: string; host: string; user?: string; pass?: string; labels: string[] };
+type Device = { id: string; type: string; name: string; host: string; user?: string; pass?: string; channels?: number; labels: string[] };
 type Relay = { number: number; label: string; on: boolean };
 type DevStatus = { id: string; name: string; type: string; connected: boolean; error?: string; relays: Relay[] };
 
-const RELAY_COUNT: Record<string, number> = { webswitch: 5, kmtronic: 8 };
-const TYPE_LABEL: Record<string, string> = { webswitch: 'WebSwitch 1216H', kmtronic: 'KMTronic 8-relay' };
+const RELAY_COUNT: Record<string, number> = { webswitch: 5, kmtronic: 8, denkovi: 8, usbrelay: 8 };
+const TYPE_LABEL: Record<string, string> = { webswitch: 'WebSwitch 1216H', kmtronic: 'KMTronic 8-relay', denkovi: 'Denkovi USB (FT245)', usbrelay: 'Denkovi USB (serial)' };
+
+// Relay count for a configured device: fixed by type, except Denkovi (4/8) and
+// the generic USB-serial board, whose channel count the user picks.
+const chanCount = (d: Device): number =>
+  (d.type === 'denkovi' || d.type === 'usbrelay') ? (d.channels && d.channels >= 1 ? d.channels : 8) : (RELAY_COUNT[d.type] ?? 5);
 
 function blankDevice(): Device {
   return { id: '', type: 'webswitch', name: '', host: '', user: '', pass: '', labels: Array(5).fill('') };
@@ -445,11 +451,39 @@ function DeviceEditor({ device, onChange, onSave, onCancel, t }: {
   const ref = useRef<HTMLDivElement>(null);
   useEffect(() => { ref.current?.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }, []);
   const setType = (type: string) => {
-    const n = RELAY_COUNT[type] ?? 5;
+    const channels = (type === 'denkovi' || type === 'usbrelay') ? (device.channels || 8) : undefined;
+    const n = chanCount({ ...device, type, channels });
     const labels = Array.from({ length: n }, (_, i) => device.labels[i] ?? '');
-    onChange({ ...device, type, labels });
+    onChange({ ...device, type, channels, labels });
+  };
+  const setChannels = (channels: number) => {
+    const n = chanCount({ ...device, channels });
+    const labels = Array.from({ length: n }, (_, i) => device.labels[i] ?? '');
+    onChange({ ...device, channels, labels });
   };
   const isKM = device.type === 'kmtronic';
+  const isDenkovi = device.type === 'denkovi';
+  const isUsbRelay = device.type === 'usbrelay';
+  // COM ports for the generic USB-serial relay picker.
+  const [serialPorts, setSerialPorts] = useState<string[]>([]);
+  useEffect(() => {
+    if (!isUsbRelay) return;
+    ListSerialPorts().then((p) => setSerialPorts((p ?? []) as string[])).catch(() => setSerialPorts([]));
+  }, [isUsbRelay]);
+  // Detected FTDI serials for the Denkovi picker.
+  const [denkoviSerials, setDenkoviSerials] = useState<string[]>([]);
+  const [detecting, setDetecting] = useState(false);
+  const detectDenkovi = async () => {
+    setDetecting(true);
+    try {
+      const list = ((await ListDenkoviDevices()) ?? []) as string[];
+      setDenkoviSerials(list);
+      // Auto-fill when there's exactly one and nothing chosen yet.
+      if (list.length >= 1 && !device.host.trim()) onChange({ ...device, host: list[0] });
+    } catch { setDenkoviSerials([]); }
+    finally { setDetecting(false); }
+  };
+  useEffect(() => { if (isDenkovi) void detectDenkovi(); /* eslint-disable-next-line */ }, [isDenkovi]);
   return (
     <div ref={ref} className="mt-4 max-w-4xl rounded-xl border border-primary/40 bg-card p-4 space-y-3">
       <div className="text-sm font-semibold">{device.id ? t('station.editDevice') : t('station.addDevice')}</div>
@@ -461,6 +495,8 @@ function DeviceEditor({ device, onChange, onSave, onCancel, t }: {
             <SelectContent>
               <SelectItem value="webswitch">WebSwitch 1216H (5 relays)</SelectItem>
               <SelectItem value="kmtronic">KMTronic 8-relay (LAN)</SelectItem>
+              <SelectItem value="denkovi">Denkovi USB (FT245 / D2XX)</SelectItem>
+              <SelectItem value="usbrelay">Denkovi USB (serial / COM)</SelectItem>
             </SelectContent>
           </Select>
         </div>
@@ -469,6 +505,54 @@ function DeviceEditor({ device, onChange, onSave, onCancel, t }: {
           <Input value={device.name} placeholder={TYPE_LABEL[device.type]} onChange={(e) => onChange({ ...device, name: e.target.value })} />
         </div>
       </div>
+      {(isDenkovi || isUsbRelay) && (
+        <div className="space-y-1 max-w-[10rem]">
+          <Label>{t('station.channels')}</Label>
+          <Select value={String(chanCount(device))} onValueChange={(v) => setChannels(parseInt(v, 10))}>
+            <SelectTrigger className="h-9"><SelectValue /></SelectTrigger>
+            <SelectContent>
+              {(isDenkovi ? [4, 8] : [1, 2, 4, 8, 16]).map((n) => (
+                <SelectItem key={n} value={String(n)}>{n}</SelectItem>
+              ))}
+            </SelectContent>
+          </Select>
+        </div>
+      )}
+      {isDenkovi ? (
+        <div className="space-y-1 max-w-md">
+          <Label>{t('station.ftdiSerial')}</Label>
+          <div className="flex items-center gap-2">
+            <Input className="font-mono flex-1" value={device.host} placeholder="DAE0006K"
+              list="denkovi-serials"
+              onChange={(e) => onChange({ ...device, host: e.target.value })} />
+            <datalist id="denkovi-serials">
+              {denkoviSerials.map((s) => <option key={s} value={s} />)}
+            </datalist>
+            <Button size="sm" variant="outline" onClick={detectDenkovi} disabled={detecting}>
+              {detecting ? <Loader2 className="size-3.5 mr-1 animate-spin" /> : <RefreshCw className="size-3.5 mr-1" />}
+              {t('station.detect')}
+            </Button>
+          </div>
+          <p className="text-[10px] text-muted-foreground">{t('station.ftdiHint')}</p>
+        </div>
+      ) : isUsbRelay ? (
+        <div className="space-y-1 max-w-md">
+          <Label>{t('station.comPort')}</Label>
+          <div className="flex items-center gap-2">
+            <Select value={device.host || '_'} onValueChange={(v) => onChange({ ...device, host: v === '_' ? '' : v })}>
+              <SelectTrigger className="h-9 flex-1"><SelectValue placeholder="— COM —" /></SelectTrigger>
+              <SelectContent>
+                {serialPorts.length === 0 && <SelectItem value="_" disabled>{t('station.noPorts')}</SelectItem>}
+                {serialPorts.map((p) => <SelectItem key={p} value={p}>{p}</SelectItem>)}
+              </SelectContent>
+            </Select>
+            <Button size="sm" variant="outline" onClick={() => ListSerialPorts().then((p) => setSerialPorts((p ?? []) as string[])).catch(() => {})}>
+              <RefreshCw className="size-3.5" />
+            </Button>
+          </div>
+          <p className="text-[10px] text-muted-foreground">{t('station.usbRelayHint')}</p>
+        </div>
+      ) : (
       <div className={cn('grid gap-3', isKM ? 'grid-cols-3' : 'grid-cols-1')}>
         <div className={cn('space-y-1', isKM ? '' : 'max-w-xs')}>
           <Label>{t('station.host')}</Label>
@@ -487,6 +571,7 @@ function DeviceEditor({ device, onChange, onSave, onCancel, t }: {
           </>
         )}
       </div>
+      )}
       <div className="space-y-1">
         <Label>{t('station.labels')}</Label>
         <div className="grid grid-cols-4 gap-2">

frontend/src/lib/i18n.tsx

@@ -131,9 +131,9 @@ const en: Dict = {
   'uscty.backfillIntro': 'Resolve county (and grid) for US QSOs already in your log that are missing them. Existing values are kept — only blanks are filled.',
   'uscty.backfillRun': 'Fill missing counties',
   'uscty.backfillDone': '{s} US QSOs scanned · {c} counties, {g} grids filled.',
-  'station.title': 'Station Control', 'station.rotator': 'Rotator', 'station.rotatorNoRead': 'No heading read', 'station.pattern': 'Pattern', 'station.bi': 'Bi', 'station.retract': 'Retract elements', 'station.moving': 'MOVING', 'station.elements': 'Elements (mm)', 'station.read': 'Read', 'station.readLengths': 'Read current element lengths from the controller', 'station.noLengths': 'Lengths unknown — click Read to fetch them from the controller.', 'station.element': 'Element', 'station.reflector': 'Reflector', 'station.driven': 'Driven', 'station.director': 'Dir', 'station.set': 'Set', 'station.elementsHint': 'Each press lengthens/shortens the element by 2 mm (like the physical console). Verify which element responds on your antenna.', 'station.setExactLen': 'Click to type the exact current length (fixes the baseline if the auto-read is off).', 'station.atMax': 'Controller refused — the element is likely at its maximum length for this band, so it can\'t extend further.', 'station.go': 'Go', 'station.stop': 'Stop', 'station.dragHint': 'Drag a widget by its card to reorder. Pick a column count to lay them out in a grid.', 'station.colsAuto': 'Auto', 'station.addDevice': 'Add device', 'station.editDevice': 'Edit device', 'station.empty': 'No relay boards yet. Add a WebSwitch 1216H or a KMTronic 8-relay board to control your station power and accessories.', 'station.online': 'Online', 'station.offline': 'Offline', 'station.edit': 'Edit', 'station.delete': 'Delete', 'station.relay': 'Relay', 'station.on': 'ON', 'station.off': 'OFF', 'station.type': 'Device type', 'station.name': 'Name', 'station.host': 'Host / IP', 'station.user': 'Username', 'station.pass': 'Password', 'station.optional': 'optional', 'station.labels': 'Relay labels', 'station.cancel': 'Cancel', 'station.save': 'Save',
+  'station.title': 'Station Control', 'station.rotator': 'Rotator', 'station.rotatorNoRead': 'No heading read', 'station.pattern': 'Pattern', 'station.bi': 'Bi', 'station.retract': 'Retract elements', 'station.moving': 'MOVING', 'station.elements': 'Elements (mm)', 'station.read': 'Read', 'station.readLengths': 'Read current element lengths from the controller', 'station.noLengths': 'Lengths unknown — click Read to fetch them from the controller.', 'station.element': 'Element', 'station.reflector': 'Reflector', 'station.driven': 'Driven', 'station.director': 'Dir', 'station.set': 'Set', 'station.elementsHint': 'Each press lengthens/shortens the element by 2 mm (like the physical console). Verify which element responds on your antenna.', 'station.setExactLen': 'Click to type the exact current length (fixes the baseline if the auto-read is off).', 'station.atMax': 'Controller refused — the element is likely at its maximum length for this band, so it can\'t extend further.', 'station.go': 'Go', 'station.stop': 'Stop', 'station.dragHint': 'Drag a widget by its card to reorder. Pick a column count to lay them out in a grid.', 'station.colsAuto': 'Auto', 'station.addDevice': 'Add device', 'station.editDevice': 'Edit device', 'station.empty': 'No relay boards yet. Add a WebSwitch 1216H or a KMTronic 8-relay board to control your station power and accessories.', 'station.online': 'Online', 'station.offline': 'Offline', 'station.edit': 'Edit', 'station.delete': 'Delete', 'station.relay': 'Relay', 'station.on': 'ON', 'station.off': 'OFF', 'station.type': 'Device type', 'station.name': 'Name', 'station.host': 'Host / IP', 'station.user': 'Username', 'station.pass': 'Password', 'station.optional': 'optional', 'station.ftdiSerial': 'FTDI serial number', 'station.detect': 'Detect', 'station.ftdiHint': 'The Denkovi board is driven via FTDI bit-bang (not the COM port). Pick its serial (e.g. DAE0006K). Needs the FTDI D2XX driver installed.', 'station.channels': 'Relays', 'station.comPort': 'COM port', 'station.noPorts': 'No ports found', 'station.usbRelayHint': 'Cheap USB-serial relay boards (CH340/LCUS) using the A0 command protocol. If yours does not switch, tell me its model / command set.', 'station.labels': 'Relay labels', 'station.cancel': 'Cancel', 'station.save': 'Save',
   'sec.awards': 'Awards', 'sec.cat': 'CAT interface', 'sec.rotator': 'Rotator', 'sec.winkeyer': 'CW Keyer',
-  'sec.antenna': 'Ultrabeam / Steppir', 'sec.antgenius': 'Antenna Genius', 'sec.pgxl': 'Power Genius', 'sec.flex': 'FlexRadio', 'sec.audio': 'Audio devices',
+  'sec.antenna': 'Ultrabeam / Steppir', 'sec.antgenius': 'Antenna Genius', 'sec.pgxl': 'Amplifier', 'sec.flex': 'FlexRadio', 'sec.audio': 'Audio devices',
   'sec.relayauto': 'Relay auto-control',
   'relayauto.hint': 'Automatically switch Station Control relays from the rig frequency / band (like PstRotator). Each relay: a frequency window (ON inside, OFF outside) or a set of bands. Relays are set up in the Station Control panel.',
   'relayauto.enable': 'Enable relay auto-control',
@@ -444,9 +444,9 @@ const fr: Dict = {
   'uscty.backfillIntro': "Résout le comté (et le locator) pour les QSO US déjà dans ton log qui n'en ont pas. Les valeurs existantes sont conservées — seuls les vides sont remplis.",
   'uscty.backfillRun': 'Remplir les comtés manquants',
   'uscty.backfillDone': '{s} QSO US analysés · {c} comtés, {g} locators remplis.',
-  'station.title': 'Contrôle station', 'station.rotator': 'Rotator', 'station.rotatorNoRead': 'Azimut non lu', 'station.pattern': 'Diagramme', 'station.bi': 'Bi', 'station.retract': 'Rétracter les éléments', 'station.moving': 'EN MOUVEMENT', 'station.elements': 'Éléments (mm)', 'station.read': 'Lire', 'station.readLengths': 'Lire les longueurs actuelles depuis le contrôleur', 'station.noLengths': 'Longueurs inconnues — clique sur Lire pour les récupérer depuis le contrôleur.', 'station.element': 'Élément', 'station.reflector': 'Réflecteur', 'station.driven': 'Radiateur', 'station.director': 'Dir', 'station.set': 'Régler', 'station.elementsHint': "Chaque appui allonge/raccourcit l'élément de 2 mm (comme le pupitre). Vérifie quel élément répond sur ton antenne.", 'station.setExactLen': "Clique pour taper la longueur actuelle exacte (recale la base si la lecture auto est fausse).", 'station.atMax': "Refusé par le contrôleur — l'élément est probablement en butée (longueur max pour cette bande), il ne peut plus s'allonger.", 'station.go': 'Aller', 'station.stop': 'Stop', 'station.dragHint': 'Glisse une carte pour réordonner. Choisis un nombre de colonnes pour la disposition.', 'station.colsAuto': 'Auto', 'station.addDevice': 'Ajouter un appareil', 'station.editDevice': "Modifier l'appareil", 'station.empty': "Aucune carte relais. Ajoute un WebSwitch 1216H ou une carte KMTronic 8 relais pour piloter l'alimentation et les accessoires de ta station.", 'station.online': 'En ligne', 'station.offline': 'Hors ligne', 'station.edit': 'Modifier', 'station.delete': 'Supprimer', 'station.relay': 'Relais', 'station.on': 'ON', 'station.off': 'OFF', 'station.type': "Type d'appareil", 'station.name': 'Nom', 'station.host': 'Hôte / IP', 'station.user': "Nom d'utilisateur", 'station.pass': 'Mot de passe', 'station.optional': 'optionnel', 'station.labels': 'Libellés des relais', 'station.cancel': 'Annuler', 'station.save': 'Enregistrer',
+  'station.title': 'Contrôle station', 'station.rotator': 'Rotator', 'station.rotatorNoRead': 'Azimut non lu', 'station.pattern': 'Diagramme', 'station.bi': 'Bi', 'station.retract': 'Rétracter les éléments', 'station.moving': 'EN MOUVEMENT', 'station.elements': 'Éléments (mm)', 'station.read': 'Lire', 'station.readLengths': 'Lire les longueurs actuelles depuis le contrôleur', 'station.noLengths': 'Longueurs inconnues — clique sur Lire pour les récupérer depuis le contrôleur.', 'station.element': 'Élément', 'station.reflector': 'Réflecteur', 'station.driven': 'Radiateur', 'station.director': 'Dir', 'station.set': 'Régler', 'station.elementsHint': "Chaque appui allonge/raccourcit l'élément de 2 mm (comme le pupitre). Vérifie quel élément répond sur ton antenne.", 'station.setExactLen': "Clique pour taper la longueur actuelle exacte (recale la base si la lecture auto est fausse).", 'station.atMax': "Refusé par le contrôleur — l'élément est probablement en butée (longueur max pour cette bande), il ne peut plus s'allonger.", 'station.go': 'Aller', 'station.stop': 'Stop', 'station.dragHint': 'Glisse une carte pour réordonner. Choisis un nombre de colonnes pour la disposition.', 'station.colsAuto': 'Auto', 'station.addDevice': 'Ajouter un appareil', 'station.editDevice': "Modifier l'appareil", 'station.empty': "Aucune carte relais. Ajoute un WebSwitch 1216H ou une carte KMTronic 8 relais pour piloter l'alimentation et les accessoires de ta station.", 'station.online': 'En ligne', 'station.offline': 'Hors ligne', 'station.edit': 'Modifier', 'station.delete': 'Supprimer', 'station.relay': 'Relais', 'station.on': 'ON', 'station.off': 'OFF', 'station.type': "Type d'appareil", 'station.name': 'Nom', 'station.host': 'Hôte / IP', 'station.user': "Nom d'utilisateur", 'station.pass': 'Mot de passe', 'station.optional': 'optionnel', 'station.ftdiSerial': 'Numéro de série FTDI', 'station.detect': 'Détecter', 'station.ftdiHint': "La carte Denkovi se pilote en FTDI bit-bang (pas via le port COM). Choisis son numéro de série (ex. DAE0006K). Nécessite le driver FTDI D2XX installé.", 'station.channels': 'Relais', 'station.comPort': 'Port COM', 'station.noPorts': 'Aucun port', 'station.usbRelayHint': "Cartes USB-série bon marché (CH340/LCUS) protocole A0. Si la tienne ne commute pas, donne-moi le modèle / jeu de commandes.", 'station.labels': 'Libellés des relais', 'station.cancel': 'Annuler', 'station.save': 'Enregistrer',
   'sec.awards': 'Diplômes', 'sec.cat': 'Interface CAT', 'sec.rotator': 'Rotator', 'sec.winkeyer': 'Manipulateur CW',
-  'sec.antenna': 'Antenne motorisée', 'sec.antgenius': 'Antenna Genius', 'sec.pgxl': 'Power Genius', 'sec.flex': 'FlexRadio', 'sec.audio': 'Périphériques audio',
+  'sec.antenna': 'Antenne motorisée', 'sec.antgenius': 'Antenna Genius', 'sec.pgxl': 'Amplificateur', 'sec.flex': 'FlexRadio', 'sec.audio': 'Périphériques audio',
   'sec.relayauto': 'Relais automatiques',
   'relayauto.hint': "Commute automatiquement les relais du Station Control selon la fréquence / bande du poste (comme PstRotator). Par relais : une plage de fréquence (ON dedans, OFF dehors) ou un ensemble de bandes. Les relais se configurent dans le panneau Station Control.",
   'relayauto.enable': 'Activer les relais automatiques',

frontend/wailsjs/go/main/App.d.ts

@@ -546,6 +546,8 @@ export function ListContests():Promise<Array<contest.Def>>;
 
 export function ListCountries():Promise<Array<string>>;
 
+export function ListDenkoviDevices():Promise<Array<string>>;
+
 export function ListOperatingTree():Promise<Array<operating.Station>>;
 
 export function ListProfiles():Promise<Array<profile.Profile>>;

frontend/wailsjs/go/main/App.js

@@ -1050,6 +1050,10 @@ export function ListCountries() {
   return window['go']['main']['App']['ListCountries']();
 }
 
+export function ListDenkoviDevices() {
+  return window['go']['main']['App']['ListDenkoviDevices']();
+}
+
 export function ListOperatingTree() {
   return window['go']['main']['App']['ListOperatingTree']();
 }

frontend/wailsjs/go/models.ts

@@ -2161,8 +2161,12 @@ export namespace main {
 	}
 	export class PGXLSettings {
 	    enabled: boolean;
+	    type: string;
+	    transport: string;
 	    host: string;
 	    port: number;
+	    com_port: string;
+	    baud: number;
 	
 	    static createFrom(source: any = {}) {
 	        return new PGXLSettings(source);
@@ -2171,8 +2175,12 @@ export namespace main {
 	    constructor(source: any = {}) {
 	        if ('string' === typeof source) source = JSON.parse(source);
 	        this.enabled = source["enabled"];
+	        this.type = source["type"];
+	        this.transport = source["transport"];
 	        this.host = source["host"];
 	        this.port = source["port"];
+	        this.com_port = source["com_port"];
+	        this.baud = source["baud"];
 	    }
 	}
 	export class POTAUnmatched {
@@ -2600,6 +2608,7 @@ export namespace main {
 	    host: string;
 	    user?: string;
 	    pass?: string;
+	    channels?: number;
 	    labels: string[];
 	
 	    static createFrom(source: any = {}) {
@@ -2614,6 +2623,7 @@ export namespace main {
 	        this.host = source["host"];
 	        this.user = source["user"];
 	        this.pass = source["pass"];
+	        this.channels = source["channels"];
 	        this.labels = source["labels"];
 	    }
 	}

internal/relaydev/denkovi_other.go

@@ -0,0 +1,34 @@
+//go:build !windows
+
+// The Denkovi USB board is driven through FTDI's D2XX bit-bang API (ftd2xx.dll),
+// which OpsLog only wires up on Windows. This stub keeps the package building on
+// other platforms; every call reports the board is unavailable.
+package relaydev
+
+import (
+	"context"
+	"fmt"
+)
+
+type denkoviStub struct{ count int }
+
+// NewDenkovi returns a stub on non-Windows builds.
+func NewDenkovi(serial string, count int) Device {
+	if count != 4 {
+		count = 8
+	}
+	return denkoviStub{count: count}
+}
+
+func (s denkoviStub) Count() int { return s.count }
+func (denkoviStub) Status(context.Context) ([]bool, error) {
+	return nil, fmt.Errorf("Denkovi USB relay board is only supported on Windows")
+}
+func (denkoviStub) Set(context.Context, int, bool) error {
+	return fmt.Errorf("Denkovi USB relay board is only supported on Windows")
+}
+
+// ListDenkovi has no devices to report off Windows.
+func ListDenkovi() ([]string, error) {
+	return nil, fmt.Errorf("Denkovi USB relay board is only supported on Windows")
+}

internal/relaydev/denkovi_windows.go

@@ -0,0 +1,185 @@
+//go:build windows
+
+// Denkovi USB 8-channel relay board (FT245RL). Despite enumerating as a virtual
+// COM port, this board is NOT driven by serial/ASCII: the FT245's 8 data lines
+// each drive a relay, controlled through FTDI's D2XX "bit-bang" mode. One byte
+// written = the 8 relays at once (bit 0 = relay 1). We load ftd2xx.dll at runtime
+// (no CGO) and call the D2XX API directly, exactly as the vendor's tool does
+// (which addresses the board by its FTDI serial, e.g. "DAE0006K").
+package relaydev
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"sync"
+	"syscall"
+	"unsafe"
+)
+
+var (
+	ftdll             = syscall.NewLazyDLL("ftd2xx.dll")
+	procOpenEx        = ftdll.NewProc("FT_OpenEx")
+	procClose         = ftdll.NewProc("FT_Close")
+	procSetBitMode    = ftdll.NewProc("FT_SetBitMode")
+	procSetBaudRate   = ftdll.NewProc("FT_SetBaudRate")
+	procWrite         = ftdll.NewProc("FT_Write")
+	procPurge         = ftdll.NewProc("FT_Purge")
+	procCreateInfo    = ftdll.NewProc("FT_CreateDeviceInfoList")
+	procGetInfoDetail = ftdll.NewProc("FT_GetDeviceInfoDetail")
+)
+
+const (
+	ftOpenBySerial  = 1    // FT_OPEN_BY_SERIAL_NUMBER
+	ftBitModeSyncBB = 0x04 // FT_BITMODE_SYNC_BITBANG (the mode Denkovi documents)
+	ftPurgeRX       = 1    // FT_PURGE_RX
+)
+
+func ftOK(r uintptr) bool { return r == 0 } // FT_OK == 0
+
+type denkovi struct {
+	serial string
+	count  int
+	mu     sync.Mutex
+	shadow byte    // last output byte (bit n = relay n+1); authoritative state
+	h      uintptr // FT handle
+	opened bool
+}
+
+// NewDenkovi builds a driver for a Denkovi USB relay board (4 or 8 relays)
+// identified by its FTDI serial number (shown by the vendor tool / FT_PROG,
+// e.g. "DAE0006K"). count defaults to 8; a 4-relay board just uses the low 4 bits.
+func NewDenkovi(serial string, count int) Device {
+	if count != 4 && count != 8 {
+		count = 8
+	}
+	return &denkovi{serial: strings.TrimSpace(serial), count: count}
+}
+
+func (d *denkovi) Count() int { return d.count }
+
+// ensureOpen opens the board and puts it in synchronous bit-bang mode with all 8
+// lines as outputs. Idempotent.
+func (d *denkovi) ensureOpen() error {
+	if d.opened {
+		return nil
+	}
+	if err := ftdll.Load(); err != nil {
+		return fmt.Errorf("FTDI D2XX driver (ftd2xx.dll) not found — install the FTDI D2XX driver / Denkovi software: %w", err)
+	}
+	if d.serial == "" {
+		return fmt.Errorf("no FTDI serial number set for the Denkovi board")
+	}
+	ser, err := syscall.BytePtrFromString(d.serial)
+	if err != nil {
+		return err
+	}
+	var h uintptr
+	if r, _, _ := procOpenEx.Call(uintptr(unsafe.Pointer(ser)), ftOpenBySerial, uintptr(unsafe.Pointer(&h))); !ftOK(r) {
+		return fmt.Errorf("cannot open Denkovi board %q (FT_OpenEx status %d) — is it connected and not in use by another app?", d.serial, r)
+	}
+	// All 8 lines output, synchronous bit-bang.
+	if r, _, _ := procSetBitMode.Call(h, 0xFF, ftBitModeSyncBB); !ftOK(r) {
+		procClose.Call(h)
+		return fmt.Errorf("FT_SetBitMode failed (status %d)", r)
+	}
+	procSetBaudRate.Call(h, 9600) // bit-bang pin-update clock; relays don't need speed
+	d.h = h
+	d.opened = true
+	// Make the hardware match our shadow (starts all-off on first open).
+	return d.writeLocked()
+}
+
+// writeLocked pushes the shadow byte to the relays. Caller holds d.mu.
+func (d *denkovi) writeLocked() error {
+	var written uint32
+	b := d.shadow
+	if r, _, _ := procWrite.Call(d.h, uintptr(unsafe.Pointer(&b)), 1, uintptr(unsafe.Pointer(&written))); !ftOK(r) {
+		return fmt.Errorf("FT_Write failed (status %d)", r)
+	}
+	// Synchronous bit-bang echoes each written byte into the RX buffer; drop it so
+	// it doesn't fill over the life of the connection.
+	procPurge.Call(d.h, ftPurgeRX)
+	return nil
+}
+
+func (d *denkovi) Set(ctx context.Context, relay int, on bool) error {
+	if relay < 1 || relay > d.count {
+		return fmt.Errorf("relay %d out of range 1..%d", relay, d.count)
+	}
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if err := d.ensureOpen(); err != nil {
+		return err
+	}
+	bit := byte(1) << uint(relay-1) // relay 1 → bit 0
+	if on {
+		d.shadow |= bit
+	} else {
+		d.shadow &^= bit
+	}
+	return d.writeLocked()
+}
+
+func (d *denkovi) Status(ctx context.Context) ([]bool, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if err := d.ensureOpen(); err != nil {
+		return nil, err
+	}
+	out := make([]bool, d.count)
+	for i := 0; i < d.count; i++ {
+		out[i] = d.shadow&(byte(1)<<uint(i)) != 0
+	}
+	return out, nil
+}
+
+// ListDenkovi returns the FTDI serial numbers of connected devices, for the
+// settings UI to pick from. Requires ftd2xx.dll.
+func ListDenkovi() ([]string, error) {
+	if err := ftdll.Load(); err != nil {
+		return nil, fmt.Errorf("FTDI D2XX driver (ftd2xx.dll) not found — install the FTDI D2XX driver / Denkovi software")
+	}
+	var n uint32
+	if r, _, _ := procCreateInfo.Call(uintptr(unsafe.Pointer(&n))); !ftOK(r) {
+		return nil, fmt.Errorf("FT_CreateDeviceInfoList failed (status %d)", r)
+	}
+	var out []string
+	for i := uint32(0); i < n; i++ {
+		var flags, typ, id, loc uint32
+		serial := make([]byte, 16)
+		desc := make([]byte, 64)
+		var h uintptr
+		r, _, _ := procGetInfoDetail.Call(
+			uintptr(i),
+			uintptr(unsafe.Pointer(&flags)), uintptr(unsafe.Pointer(&typ)),
+			uintptr(unsafe.Pointer(&id)), uintptr(unsafe.Pointer(&loc)),
+			uintptr(unsafe.Pointer(&serial[0])), uintptr(unsafe.Pointer(&desc[0])),
+			uintptr(unsafe.Pointer(&h)),
+		)
+		if !ftOK(r) {
+			continue
+		}
+		if s := cstr(serial); s != "" {
+			out = append(out, s)
+		}
+	}
+	return out, nil
+}
+
+// cstr trims a C string (up to the first NUL) from a fixed buffer.
+func cstr(b []byte) string {
+	if i := indexByte(b, 0); i >= 0 {
+		b = b[:i]
+	}
+	return strings.TrimSpace(string(b))
+}
+
+func indexByte(b []byte, c byte) int {
+	for i := range b {
+		if b[i] == c {
+			return i
+		}
+	}
+	return -1
+}

internal/relaydev/serialrelay.go

@@ -0,0 +1,89 @@
+package relaydev
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"sync"
+
+	"go.bug.st/serial"
+)
+
+// serialRelay drives the common cheap USB-serial relay boards (CH340 / LCUS-1
+// style) that use the "A0" command protocol over a virtual COM port:
+//
+//	[0xA0] [relay 1-based] [state 0|1] [checksum]     checksum = (0xA0+relay+state) & 0xFF
+//
+// e.g. relay 1 ON = A0 01 01 A2, relay 1 OFF = A0 01 00 A1. These boards are
+// write-only (no state readback), so Status reflects a shadow of what we sent.
+// Channel count varies by board (1/2/4/8/16), so it is configurable.
+type serialRelay struct {
+	portName string
+	count    int
+	baud     int
+	mu       sync.Mutex
+	port     serial.Port
+	shadow   []bool
+}
+
+// NewSerialRelay builds a driver for a CH340/LCUS-style USB-serial relay board on
+// the given COM port with `count` channels (defaults to 8).
+func NewSerialRelay(port string, count int) Device {
+	if count < 1 {
+		count = 8
+	}
+	return &serialRelay{portName: strings.TrimSpace(port), count: count, baud: 9600, shadow: make([]bool, count)}
+}
+
+func (s *serialRelay) Count() int { return s.count }
+
+func (s *serialRelay) ensureOpen() error {
+	if s.port != nil {
+		return nil
+	}
+	if s.portName == "" {
+		return fmt.Errorf("no COM port set for the USB relay board")
+	}
+	p, err := serial.Open(s.portName, &serial.Mode{BaudRate: s.baud})
+	if err != nil {
+		return fmt.Errorf("open %s: %w", s.portName, err)
+	}
+	s.port = p
+	return nil
+}
+
+func (s *serialRelay) Set(ctx context.Context, relay int, on bool) error {
+	if relay < 1 || relay > s.count {
+		return fmt.Errorf("relay %d out of range 1..%d", relay, s.count)
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if err := s.ensureOpen(); err != nil {
+		return err
+	}
+	st := byte(0)
+	if on {
+		st = 1
+	}
+	r := byte(relay)
+	frame := []byte{0xA0, r, st, byte(0xA0) + r + st} // last byte = checksum
+	if _, err := s.port.Write(frame); err != nil {
+		// Drop the handle so the next call reopens (USB unplugged / port reset).
+		s.port.Close()
+		s.port = nil
+		return fmt.Errorf("write to %s: %w", s.portName, err)
+	}
+	s.shadow[relay-1] = on
+	return nil
+}
+
+func (s *serialRelay) Status(ctx context.Context) ([]bool, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if err := s.ensureOpen(); err != nil {
+		return nil, err
+	}
+	out := make([]bool, s.count)
+	copy(out, s.shadow)
+	return out, nil
+}