A K3NG controller answered PuTTY perfectly and told OpsLog 'no reply to
C'. The reason is not the protocol: the client opened and CLOSED the
serial port for every single command, and an Arduino-based controller
resets when its port is opened — DTR pulses the reset pin. OpsLog was
rebooting it several times a second, and every command it sent landed in
a bootloader.
The port is opened once and held, per COM port, at package level: the
callers build a fresh Client per poll, so the port has to outlive them,
and a serial port is a single-owner resource in any case. A newly opened
port is given two seconds to boot before the first command, bytes left
from a previous exchange are drained rather than read as this command's
answer, and a failed exchange drops the port so the next starts from a
clean open instead of repeating the same silence.
Reply parsing was already right for both flavours and now has the real
strings to prove it, that controller's '+0140' among them.
rouggy
ec347e1b7a