What is the difference between PR55-34 and PR55-34M

I have (2) PR55-34 and looking to purchase a few more units that will connect the gateway to modbus devices. First what is the difference between PR55-34 and the PR55-34M? I also want to read a float switch in addition to the modbus RTU device that will be attached to the PR55-34 device. Since it is a simple contact in the float switch I would just need to connect to the GPIO on the 900MHZ board but there are no places to do that on your board. Can I avoid buying the PR52-18DI? I have another application needing an output relay but again there isn’t a spot to connect to the GPIO pins on the board.

PR55-34 – its a wirelss-RS485 bridge. think of replacing a long wire with a wireless link.
PR55-34F – connect to any modbus slave device and set the reg you want to read and the read interval, it will read that and send over wireless to a gateway. https://ncd.io/blog/configuring-modbus-rtu-transmitter-with-node-red/

These converters do no have any GPIO.
this could be used to read a GPIO

@Bhaskar

  1. When wireless-RS485 bridging; can a single PR55-34 be connected to multiple slave devices?
    1a. Can your Enterprise IIoT Gateway act as the wireless-RS485 master or do I another PR55-34 connected to the Gateway?

  2. I have a Modbus device that, unfortunately, needs a coil write to trigger new data before new data can be read from the input registers . Can the PR55-34M be configured to write to a coil and then read on a time interval? I would love to just get the RS485 converted to a NCD wireless device so I can integrate more Enterprise sensors :grin:

Thanks!

  1. Yes it can. it doesn’t care about the RS485 data.
  2. Yes Enterprise gateway
  3. we will need to add the write function. let me know the write function code you are using and does it need to write to that reg before every read ?

@Bhaskar
Yes the write is required before every read attempt.
Below is a manual excerpt of the loop suggested by the manufacture of the RS485 device.
image

write to Function code 05 Reg 0001
delay
Read from Function code 04 Reg 30201 Size 6
and
Read from Function code 04 Reg 30211 Size 6
repeat

I current use this loop with node-red and a Modbus RTU to TCP converter.