MVI56-MCMR PROSOFT

Model: MVI56-MCMR
Brand: ProSoft Technology
Series: MVI56 (ControlLogix in‑chassis communication)
Core Function: Remote Modbus master/slave link for serial Modbus devices
Type: Modbus Master/Slave Serial Communication Module (Reduced Data Block)
Key Specs: 2 serial ports, up to 5,000 registers, 800 mA @ 5 V, 0–60 °C

Product Introduction

This is a peer‑to‑peer note. The ProSoft MVI56‑MCMR is essentially the remote‑rack version of the classic ControlLogix Modbus serial module: it gives you two Modbus RTU/ASCII ports and a reduced but still sizable data block, accessible from a Logix CPU over the backplane or via networked remote I/O. It is meant to sit in a local or remote 1756 rack and present serial Modbus devices to the controller as a structured database rather than ad‑hoc serial reads.

You typically pick MVI56‑MCMR when you want Modbus serial hanging off a remote rack (for example, out in a field junction box or MCC) and you do not need the full “big” data block of the original MVI56‑MCM. The module can move up to 5,000 registers in and out of the processor, with sample applications using around 600 words each way, and it pulls roughly 800 mA @ 5 V in an environment between 0 and 60 °C, so you must actually run the power and thermal math instead of assuming the rack will cope.

Key Selling Points & Differentiators

Two independent Modbus serial ports (RTU/ASCII, each master and/or slave) let a single module talk to multiple Modbus segments or act as both a master polling field devices and a slave to a higher‑level Modbus system.
The reduced‑block architecture still supports up to about 5,000 16‑bit registers to/from the ControlLogix CPU, which is plenty for most serial Modbus applications in a remote rack, while keeping the memory footprint manageable in Logix tags.
Using an in‑rack ProSoft module keeps the data exchange synchronous with the Logix backplane rather than relying on small protocol gateways with yet another configuration environment and power feed.
Not recommended for greenfield designs where your field devices are already Ethernet‑native; in that case, Modbus TCP or EtherNet/IP modules plus Ethernet‑capable instruments usually make more sense than adding new serial networks.
For spares, “New Original (New Surplus)” or “Refurbished (tested)” is viable only when backed with a test report showing power‑on, Modbus master and slave transactions on both ports, and at least 24 hours of continuous run.
As a remote module, the MVI56‑MCMR also depends on the health of the remote rack link (EtherNet/IP or ControlNet); you need to treat the comms path as part of the overall reliability, not just the Modbus card itself.