Description
ProSoft MVI56-MDA4 | ControlLogix CM4 Gas Analyzer Master Module
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | ProSoft Technology |
| Model | MVI56-MDA4 |
| Product Type | MDA Scientific CM4 Master Module |
| Host Platform | Rockwell Automation ControlLogix |
| Form Factor | Single-slot 1756 backplane |
| CM4 Master Ports | 2 |
| Application Interfaces | RS-232 / RS-422 / RS-485 |
| Baud Rate | 110 to 115,200 baud |
| Data Bits | 5 to 8 |
| Stop Bits | 1 or 2 |
| Parity | None, Odd, Even |
| CM4 Slaves | 1 to 10 configurable |
| Register Database | Up to 5,000 registers |
| CFG Port | RJ45, RS-232 |
| Application Connectors | RJ45 |
| Backplane Load | 800 mA @ 5 VDC; 3 mA @ 24 VDC |
| Operating Temperature | 0 to 60°C |
| Storage Temperature | -40 to 85°C |
| Relative Humidity | 5–95%, non-condensing |
| Isolation | 500 V optical isolation from backplane |
The OEM documentation specifies two CM4 master ports with configurable baud rate, parity, data bits, stop bits, RTS timing, CTS operation, response timeout, slave count, protocol version, and polling delay.
Product Introduction
The ProSoft MVI56-MDA4 is an in-chassis communication module that allows a Rockwell Automation ControlLogix processor to communicate with MDA Scientific CM4 gas-monitoring hardware. It operates as the interface between the ControlLogix backplane and the CM4 network, with an internal 5,000-word register space used for data exchange.
The module provides two CM4 master ports and can actively issue CM4 commands to connected devices. The OEM manual documents four read commands and five write/control commands, making the module more than a simple serial converter; it performs application-specific CM4 master functions and exchanges the resulting data with ControlLogix ladder logic.
MVI56-MDA4
Application Scenarios & Field Pitfalls — Engineer’s Perspective
Engineering Pain Point
A failed MVI56-MDA4 can interrupt the data path between a ControlLogix controller and a CM4 gas-monitoring network. A communications fault should not automatically be attributed to the module because serial wiring, CM4 slave configuration, polling parameters, ladder logic, and ControlLogix backplane configuration can produce similar symptoms.
Typical Applications
- MDA Scientific CM4 gas-monitoring systems
- ControlLogix-based gas detection and monitoring systems
- Industrial process monitoring
- Legacy safety or environmental monitoring installations using CM4 hardware
Technical Pitfalls to Avoid
- Do not confuse MVI56-MDA4 with a generic Modbus module.
Although its physical serial interfaces support RS-232, RS-422, and RS-485, its application driver is specifically designed for the MDA Scientific CM4 protocol. The OEM documentation describes dedicated CM4 read, write, and control commands. - Preserve the ladder-logic data structure.
The module exchanges data with the ControlLogix processor through input/output images and module registers. ProSoft provides sample ladder logic, and the application configuration is downloaded to the module from a configuration file. - Check the serial configuration before replacing hardware.
Baud rate, parity, data bits, stop bits, RTS timing, CTS usage, response timeout, slave count, protocol version, and polling delay are configurable. A replacement with factory-default settings may not communicate with the existing CM4 network until the original configuration is restored.
Related Products
- ProSoft MVI56-MDA16 — Related ControlLogix MDA Scientific CM4 solution intended for larger System 16 configurations.
- ProSoft MVI56-MNET — ControlLogix in-chassis module for Modbus TCP applications; different protocol and application role.
- Rockwell 1756-L6x — ControlLogix processor family commonly used with 1756 in-chassis communication modules.
- Rockwell 1756 chassis — Provides the ControlLogix backplane used by the .
- MDA Scientific CM4 — Gas-monitoring platform directly interfaced by the .
- ProSoft Configuration Builder — Configuration software required for configuring the according to the OEM documentation.
Procurement Check
Before approving a replacement, verify:
- Exact model:
- ControlLogix 1756 chassis compatibility
- Existing slot assignment
- CM4 equipment model and network configuration
- Two-port serial requirement
- RS-232, RS-422, or RS-485 wiring
- CM4 slave addresses
- Baud rate and serial parameters
- Protocol version
- Polling and timeout settings
- Existing ControlLogix ladder logic
- Configuration file
- Firmware revision
- LED status and communication history
- Replacement unit’s tested condition
Recommended procurement description:
ProSoft Technology MDA Scientific CM4 Master Module, ControlLogix 1756 In-Chassis Communication Module, Two CM4 Master Ports, RS-232/RS-422/RS-485, 5,000-Register Database.
The critical compatibility point is that is an application-specific CM4 master, not a generic serial communication card. For a field replacement, preserve the original configuration file and ControlLogix ladder implementation along with the physical module.
