OK, just returned from the workshop and I couldn't get any communication on J11 (expected RS232)
Connection tested using serial params 19200,8,EVEN,1, I've tried several ModBus ASCII apps, even sending a single command as per serial reference doc - no response from the plasma unit.
I think the issue might be in "ENABLE SIGNAL". I've tried to leave it not connected, supply 3.3V to it or connect it to the ground - no joy.
Are there are any proud owners of RS485 board here who have any electronic knowledge and are willing to check how this signal is connected on the original board?
Maybe I've gotten lost in the thread... but what exactly are you trying to achieve?
Initially, I was expecting that data available over ModBus / serial link might be sufficient to make PlasmaC act as THC (e.g. by reading arc voltage and adjusting torch hight). That was clarified by Tommylight as a not appropriate approach.
Looking on the pinout make me curious and check if signals on connector J11 on the mainboard are RS232 (3.3V TTL to be more specific) and if those signals can be used for ModBus coms without the original extension board.
