Communication of Modbus Flowmeters using Micro850

[Ihtisham]

Hello.

I want to use micro850 to read and write registers from 120 modbus tcp devices.

I want to know if anyone that implemented such a solution before. If yes, how would the network architecture look like? Would I need a Modbus to Ethernet IP gateway in between?

 

[Old Man]

I use Modbus Tcp to communicate to several different devices. (But not 120 different devices) the only problem that I have ran into is trying to access (reading and or writing) to-to many addresses too FAST.

Once I slowed things down everything work just as it should.

I think depending on the total number of registers you will be working with and the speed at which you need to evaluate the results will come into play.

Want else is this Plc going to be controlling?

 

[5618]

As long as the data isn't too time critical, I don't see any reason for that to be a problem. You will have to implement some message sequencing. You would need to develop some message sequencing.

No more than four MSG_MODBUS2 can be processed in one scan. The limit is 16 open Modbus TCP connections at a time, but I don't recommend pushing that. I would prefer to limit communication to one device at a time, then when that completes message the next device. You should add some error handling to close a message if the node is offline.

The 850 handles Modbus TCP, so you should not need an additional gateway. The only reason I would expect to use a gateway is if the data is very time critical, then I might look at a ProSoft module to handle the communication with the devices and aggregate the data to then be read by the 850. It might take multiple modules to do 120 devices. I doubt you need that if you're looking at doing this with an 850.