Allen-Bradley 1769-SM2 CompactLogix DSI Modbus Communication Module

The Allen-Bradley 1769-SM2, also cataloged as the 1769-SM2 Communication Module, operates as a dedicated hardware component for direct drive communication and protocol translation across EtherNet/IP and DSI/Modbus RTU serial links within CompactLogix platforms.

Hardware Specifications

Backplane Bus & Deterministic Network Execution

The module transfers motion control data across the 1769 Compact I/O backplane bus communication velocity framework, establishing deterministic parameter updates between CompactLogix controllers and downstream PowerFlex drives. Internal firmware flash compatibility ensures real-time profile mapping across all 3 independent channels while execution loops update command registers without backplane latency. System configuration routines leverage EtherNet/IP deterministic networks to pass drive status, speed references, and fault diagnostics directly into the controller image table. Advanced onboard processing enables I/O density scaling across multi-drive topologies while maintaining galavanic isolation across serial communication lines.

Frequently Asked Questions

Q: What is the strict power supply distance rating required when positioning this module on a 1769 backplane?

A: You must install the module within 4 slot locations of the system power supply. Placing the unit beyond 4 slots leads to voltage drop across the 5 VDC rail, causing communication drops or bus faults on the serial channels.

Q: How many PowerFlex 4-Class drives can a single module manage simultaneously in Multi-Drive Mode?

A: The module supports up to 5 PowerFlex 4-Class drives per channel across its 3 RJ45 channels, allowing a single module to command up to 15 drives total in Multi-Drive Mode.

Q: What mounting options exist for panel installation when standard DIN rail mounting is not utilized?

A: You can panel-mount the unit directly to an enclosure backplate using two #8 or M4 panhead screws, maintaining rigid mechanical stability under industrial vibration conditions.

Field Installation Guidelines

Mount the module on an IEC standard DIN rail or secure it to a flat metallic panel using M4 or #8 panhead screws. Ensure surrounding air temperature inside the control cabinet remains between -10 and 50 deg C.

Plug factory-terminated RJ45 patch cables into the designated channel connectors to interface with PowerFlex 4-Class drive DSI ports. Keep signal cable runs separated from high-voltage motor power leads and AC distribution wiring to eliminate electromagnetic noise coupling.

Connect shield drain wires from communication cables directly to the main cabinet chassis ground point using low-impedance grounding clamps. Verify that overall line termination impedance complies with RS-485 Modbus RTU specifications across long multi-drop cable spans.