The Industrial Raspberry Pi Forum

Hi, I'm new in the forum,
Before considering a purchase for a first prototype I would like to have some information:
a) Is possible to set the RevPi Core as a MODBUS RTU slave (the master is an Industrial PC) and as a MODBUS RTU master (connected to several slave devices?) at the same time?
b) I understand that using the two USB ports and your USB - RS485 Converter you have two RS485 ports. However, from the website I see the the screw connector has only 2 inputs, Where I put the ground signal of the RS485 network?
c) also I'mo wandering if it is possible to use the as RS485 the PiBridge cnnectors for third parties modbus rtu devices?
Thank you very much
Aronne

Hi Aronne and welcome to the RevolutionPi Community. With interest I am looking at your questions.
a) If you provide different RS485 interfaces then yes you can use Modbus RTU Slave and Modbus RTU Master at the same time.
So the RevPi Connect already includes one RS485 interface at the front. But you can extend the interfaces i.e. by one or more USB 2.0 to 2 x serial RS-422/485 adapters.

b) Have a look at this tutorial How to Connect Serial Devices. There you can see the GND pin.
But basicaly RS485 uses differential signal transmission so maybe you don't have to use the GND pin. Some cheap USB-RS485 devices really omit this pin like this here: USB - RS485 Converter

c) You may connect a RevPi Gate Modbus TCP Slave here. But you can have raw access to the RS485 interface of the PiBridge. Then have a look at the schematics at the Downloads section. Then you have to disable the PiControl driver. Then you can access the PiBridge pins. Have a look at the Maker-Set which provides all the plugs and a case for your ideas.