Allen-Bradley 1756-L55 controller to communicate with MVI56-MCM

can we use Allen-Bradley 1756-L55 controller to communicate with MVI56-MCM Modbus communication module

What firmware is your controller using?...

Hi and Welcome to the Forum!

The older 1756-L55 processor is supported up as far as firmware revision 16. So it is also supported up as far as RSLogix 5000 v16.

Even though your 1756-L55 might be using an older firmware revision, the reason I am mentioning it is supported up to v16 is because that is when the Add-On Instruction (AOI) feature was introduced.

This is relevant because at v16 an Add-On Instruction (AOI) was introduced by Prosoft specifically for the MVI56(E)-MCM module to greatly assist in handling the module's raw I/O data, processing it and passing it to the controller. The encapsulated logic for the AOI is quite involved and can save a user hours of figuring out and writing logic, or their own AOI.

The AOI will also expose the MCM configuration parameters via tags, which is very useful.

In RSLogix v16, we can select a module profile (which was created for v15 and up) for the MVI56E-MCM (before that we had to create a 1756 Generic module). This module profile will add the module-defined data types for the input and output data for the module (both large INT arrays).

The Add-On Instruction will then, once you have it configured for your module I/O tags, interact with the module I/O data and do as I mentioned above.

So the current firmware revision of the controller will be important in deciding what level of support for all or any of the above will be available?

If you are at firmware revision 16, then please see the following Prosoft webpage for relevant downloads...

Modbus Master/Slave Enhanced Network Interface Module for ControlLogix
MVI56E-MCM/MCMXT

Regards,
George

To add to Geospark, below is a link to the MVI56-MCM legacy files.
I think the user manual docs even state how to use it with v15 and older firmware.

https://www.prosoft-technology.com/...ation-In-Chassis/MVI56-ControlLogix/MVI56-MCM

Oh, good man! I have that User Manual open here since earlier but I forgot to directly link to it in my first post, although it is also available via the links we've provided.

The older MVI56-MCM (not Enhanced) model is supported in the v16 AOI (Add-On Instruction) and v15 AOP (Add-On Profile) downloadable via the links we have provided, even though it is listed and referred to as "MVI56(E)-MCM" in most places we look (E = Enhanced model).

And yes, as I mentioned, if you are using older than version 15, and do not want to or cannot upgrade the processor firmware, then you will have to add it as a 1756-MODULE (Generic Module), as per the manual, and will also not have the AOI available to use.

If not at revision/version 16, I would highly recommend getting there, if you can.

I've also just checked and the downloadable AOI is v2.8 from either source location.

The EDS from your linked source is v1.0 of the EDS file and is specific to the non-Enhanced model MVI56-MCM.
The EDS from my linked source is v3.1 of the EDS file and is specific to the Enhanced model MVI56E-MCM.
Other than File/Device descriptions though, the contents of the EDS file are identical for Classification and Modular definitions.
But I would recommend using the older EDS for the MVI56-MCM (KuulKuum's link), if interested in it.

Regards,
George

Thank you sir