MVI56-MCM

[Shamus 0]

Hello I've been given the task of fitting an MVI56-MCM Modbus card (master) to a CLX system in order to pick up some digital signals and analog signals from and Energair compressor (slave). I've downloaded the example program from Prosoft and have implemented this in the existing program, fitted the card and powered the PLC back up. Everything seems to be ok with the correct led's on etc and the program appears to be doing something!! The problem is i don't know how much the program is doing for me and how much i still need to do to get the data from the compressor. Having looked at the compressor end it requires a message request (2 words) containing slave number, function code, number of bytes, length of bytes etc. With this get data request there is an answer. The problem Is i've not done any modbus before so could do with some pointers on the concept. I have read the manuals from Prosoft which are a bit on the heavby side but i'm thinking the genral idea is to send a command from the CLX via the MCM to the Energair and look at the answer in the MCM? Any help would be great. regards Shamus

[mellis 0]

The manual is a bit daunting. The sample program takes care of copying data to and from the MVI56-MCM. You have to set up the command list for your particular device. However, Prosoft's tech support is excellent. I'd recommend you take a shot at configuring the command list for your device and then call Prosoft and have them walk you through it and see what you missed. There is even a chance they are familiar with the device you are talking to. They were very helpful to me when I used the MVI56-MCM the first time. Good luck,

[Ghettofreeryder 0]

Yeah I use the MCM card frequently. After you set one up, its really easy

[Ken Roach 194]

I have used the MVI56-MCM extensively as well. The learning curve is steep but it makes sense once you get your head around it. You'll be using one port and configuring it to be a Modbus RTU Master, and configuring one or more entries in the Master Command list. Can you post the Modbus function codes and memory addresses the compressor maker specifies, and maybe post your ControlLogix / MVI56MCM code ? I especially like the diagnostic port on the MVI56-MCM. It really helps me see what data is going by on the link without getting an analyzer into the mix.

[Shamus 0]

Thanks very much for the replies. I'm still waiting to here from the Energair Comm Box (Slave) people so i will post details as soon as. regards Shaun