Hello,
is there probably a problem with rs232 interface?
I have following situation:
I use serial connection (Modbus RTU server with 9600Baud) over rs232 interface to NetDCUA9.
* When I first switch on NetDCUA9 and then the Modbus RTU server, everything works fine.
* When the order is changed - I switch first on the Modbus RTU server and then the NetDCUA9, I can never establish a connection. Also after several starts of the software on NetDCUA9. Only when I stop and start the service on Modbus RTU server, a connection is established.
I can open the COM2: port and send data - seems to work, but no reaction on server - also I never receive something on NetDCUA9.
Reset of COM2 port after start and several reconnects didn't help on NetDCUA9 side.
The same problem I have with other hardware with Modbus RTU server (customer machine).
The problem is still there, when I remove serial cable and insert again.
Do you have any idea, what could cause this problems and how I could solve that?
By the way, I use the latest V3.8 kernel.
New info 30.08.2024
I have made some tests and find out an important detail.
After power on of the board, the serial interface sends automatically the value 0x00.
This causes the Modbus RTU server to block. No further requests will be answered. Only after restart of server, when no 0x00 received, server works as expected.
Is it somehow possible to avoid to send something on NetDCUA9 board at power on?
Thanks a lot.
Best regards, Andy
