RS485 Output to NI9871 RS485 Module, Adapter needed?

[James.M]

I have a device sending out an RS485 signal. It is a Multitek MultigGen M820-GM. It has a pinout labeled RS485 output "+", "-", and "S".

I've attached a manual "MultiGen Manual - 8xx.pdf". Page 71 has the pinout I above. I have also followed the setup instructions on page 43 for the RS485 output and matched them in my code. (snippet attached)

I have the NI 9871 module on my cRIO, which has 4 ethernet ports. I've wired directly from the + and - outputs of the device to the RX + and - wires on an ethernet cable and don't see anything.

Do I need an adapter to make this work? The module's page here on ni.com doesn't have any accessories listed, but maybe I'm missing something. I don't have much experience with modbus, rs485, or ethernet in general.

Thank you,

[James.M]

I've looked in to a little bit further and I don't think an adapter is required... The picture here on the NI's website has a cable going straight from ethernet to RS485 without an adapter. The module itself has a power input, so I believe this means the module itself has some circuitry that takes care of this.

[MarkCG]

the 9871 definitely needs a power input on that connector in the front of the module. Also make sure you use a VISA property node to configure the wire mode of the port-- it is 4-wire mode by default, it sounds like you need 2 wire mode.