Is the DB9 port a standard serial port? I have a USB<->Serial adapter plugged into it, and am attempting to read it (first anything I've done with modbus ever), but can't seem to get it to work. I know the serial adapter works because it is working on my MPPSolar inverters.
root@raspberrypi:~# mbpoll -c 125 -o 10 /dev/ttyUSB0 -b 9600 -d 8 -s 1 -P none -R -F -v
debug enabled
Set mode to RTU for serial port
Set device=/dev/ttyUSB0
mbpoll 1.0-0 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright 2015-2019 Pascal JEAN,
https://github.com/epsilonrt/mbpoll
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions; type 'mbpoll -w' for details.
Opening /dev/ttyUSB0 at 9600 bauds (N, 8, 1)
Set response timeout to 10 sec, 0 us
Protocol configuration: Modbus RTU
Slave configuration...: address = [1]
start reference = 1, count = 125
Communication.........: /dev/ttyUSB0, 9600-8N1
t/o 10.00 s, poll rate 1000 ms
Data type.............: 16-bit register, output (holding) register table
-- Polling slave 1... Ctrl-C to stop)
[01][03][00][00][00][7D][85][EB]
Sending request using RTS signal
Waiting for a confirmation...
ERROR Connection timed out: select
Read output (holding) register failed: Connection timed out
I have a feeling it isn't a standard DB9 because I never see any bits back.