Hypertherm board pinout for RS485 extension board

If there would be a flow control required then it would be in the RS485 serial link spec and I do not see it - baud rate, data, parity and stop bits are specified, but not the flow control.

The other aspect is that usually if I'm working with printers or other devices with CTS/RTS, supplying +V or connecting those signals to the ground tricks the device and makes it think that there is a valid signal and the communication can commence.

I have all of the pins from J11 at the back of the unit now, so I can come back to it and can keep digging and checking other theories.

If you have a look at the UART on an Odroid H2+, it has 4 pins RX, TX, RTS, CTS. You are not talking about the RS485 part here but the interface to the Hypertherm's UART> Perhpas you can trace back to a chip on the board inside the plasma cutter and pull a data sheet. So long ago since I played with serial ports!

radek_marko wrote: 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.

Maybe over the weekend I'll see if I cant take my PMX apart and get you a pic of the RS485 board. Not sure if it would help or not. But it would be interesting if this really was just a 232 to 485 converter.

as I recall though the board is covered in a thick conformal coating.

I have revisited this project with a direct RS232 TTL 3.3V to USB converter to eliminate RS485 element from the equation, but still no luck .


Looktween thing on the pinout I'm wondering - why the pin +3.3V is called "INPUT". Using multimeter I've checked that there is +3.5V between this pin and the ground.

Does anyone have a faulty Hypertherm board and can trace those pins?

I always wondered how the enable worked. I figured it was to do some kind of handshaking between the Hypertherm RS232 board and the machine to prevent bypassing their hardware.

There is an interesting little board here www.mikroe.com/rs485-3-click
It presents the correct RS485 pins It might be possible to get one of these working.