Fanuc Matra model I transmission problem after power board replacement

Hello,

Two weeks ago I have replaced "Power supply board" in the machine as it was damaged.

After replacement, I had to insert all machine parameters again because I had to initialize bubble memory.

I was kinda lucky because I saved all the parameters when the machine worked properly.

After the parameters are set, machine functionality is back on everything except for communication.

Communication PC to Machine over rs232 does not work but it worked before. I am really stuck here as I don't know what else to check?

Looking forward to any advice,
Thanks in advance