Pmod485 Connection

[narvain]

I am trying to use a Pmod485 (P/N 410-310) to connect an Arduino (TTL) to a motor controller (RS485).  I am only using 1 Pmod485 and I am assuming I do need to short JP1, is this done just by sliding the blue cap over both pin headers?

 

Also, the IC block diagram shows 2 separate GND (GND1 and GND2) but the module only has 1 GND available on the pin header.  Does this mean both GND on the IC are connected together?

pmod_pmod_pmodrs485_rm.pdf

[Ana-Maria Balas]

Hello @narvain,

Pmod RS485 is used for communication via RS-485 protocol. So I assume that the motor controller uses the same protocol.

Yes, JP1 jumper is loaded by connecting both pin headers with the blue cap. JP1 jumper is loaded on the Pmod-RS485 to enable the 120 ohm termination resistor for the reliability of the transmission.

Please see the schematic of the Pmod RS485 https://reference.digilentinc.com/_media/reference/pmod/pmodrs485/pmodrs485_sch.pdf?_ga=2.267621966.193561923.1588662571-180711290.1584371590

As you can see only GND1 is connected to the GND of the Pmod header. GND2 pins are not loaded and you also can verify that by looking at the J1 on the Pmod.