Prosoft MVI69L-MBS Modbus Serial Module

The Prosoft MVI69L-MBS is a single-slot Modbus serial communication module for Rockwell Automation CompactLogix controllers (1769-L3x, L4x). It provides one configurable RS-232/485 serial port that can operate as a Modbus RTU master or slave, allowing CompactLogix systems to communicate with a wide range of Modbus-compatible devices such as drives, power meters, scales, and temperature controllers.

Modbus Master/Slave Operation

In master mode, the module can initiate read/write commands to up to 100 Modbus slave devices, executing commands sequentially or conditionally based on data values. Each command can read/write coils, discrete inputs, input registers, or holding registers. In slave mode, the module responds to Modbus requests from an external master, providing access to a 5000-word data table that is mapped to CompactLogix controller tags.

CompactLogix Integration

The module is configured as a generic 1769 module in the CompactLogix I/O configuration tree. Data is exchanged using a simple block transfer mechanism or via scheduled data exchange (produced/consumed tags). Prosoft provides sample ladder logic and AOIs to simplify integration. The module supports floating-point data conversion and byte-swapping for endianness compatibility.

Diagnostics and Configuration

The MVI69L-MBS includes an RS-232 debug port for module configuration, firmware updates, and real-time diagnostics. The Prosoft Configuration Builder software provides an intuitive interface for setting up Modbus commands, data mapping, and serial parameters. LED indicators on the front panel show module status, serial activity, and error conditions.

Application Domains

This module is widely used in water treatment, building automation, solar power plants, and factory automation where CompactLogix controllers must interface with Modbus RTU devices such as VFDs, power meters, and gas detectors.