1769-SM2 Communication Module – Installation and Technical Guide for CompactLogix Systems
Product Introduction
The Allen‑Bradley 1769‑SM2 serves as a communication gateway within the Compact I/O platform. This single‑slot module enables a CompactLogix or MicroLogix 1500 controller to communicate over the Drive Serial Interface (DSI) or implement Modbus RTU protocols. It supports direct connectivity to PowerFlex 4‑class drives and, via a 20‑COMM‑H adapter, to PowerFlex 7‑class drives. The 1769‑SM2 accommodates both single‑drive and multi‑drive operating modes, making it versatile for various drive control applications. You can mount this module directly on the DIN rail or panel, alongside other Compact I/O modules, to minimize cabinet space.
Core Value
This module reduces system complexity by integrating drive control directly into the standard I/O backplane. Specifically, the 1769‑SM2 provides a direct 1769 platform connection for DSI and Modbus networks, eliminating the need for separate gateway hardware. Consequently, you can lower overall material costs and simplify your control architecture. Moreover, the module supports both half‑duplex and full‑duplex Modbus configurations, which gives you flexible communication options for legacy and modern equipment. Furthermore, the 1769‑SM2 reduces programming overhead because it maps drive parameters directly into the controller’s tag database.
Technical Insights
Firstly, the 1769‑SM2 uses a 10/100 Mbps Ethernet port for configuration, though it is not an EtherNet/IP adapter. Secondly, the module supports baud rates up to 115.2 kbps for Modbus RTU and up to 500 kbps for DSI connections. Additionally, you can configure the 1769‑SM2 as a Modbus master or slave, depending on your network topology requirements. Meanwhile, it provides LED status indicators for power, network activity, and fault conditions, which enable rapid on‑site diagnostics. Specifically, the module’s onboard memory stores up to 32 drive parameter sets, allowing you to swap drives without reprogramming each parameter individually. Therefore, you gain significant time savings during system commissioning.
Installation & Maintenance
Begin by powering down the CompactLogix chassis before inserting the 1769‑SM2 into any available slot. Next, secure the module using the integrated DIN‑rail latches or panel mounting screws. After installation, connect the DSI or RS‑485 wiring to the removable terminal block, paying close attention to shielding and grounding to avoid noise issues. For routine maintenance, we recommend inspecting the terminal connections every six months for signs of corrosion or loosening. Besides that, periodically check the module firmware version via the RSLogix 5000 software to ensure compatibility with newer PowerFlex drive firmware. If communication errors occur, first verify the baud rate and parity settings match between the 1769‑SM2 and the target drive.
Buyer’s Guide FAQ
Q1: Which controllers are compatible with the Allen‑Bradley 1769‑SM2?
A: The 1769‑SM2 works with CompactLogix 1769‑L3x, 1769‑L2x, and MicroLogix 1500 controllers that have a 1769 backplane. It does not support ControlLogix or older SLC platforms.
Q2: Can the 1769‑SM2 communicate with non‑Rockwell drives?
A: Yes, when configured in Modbus RTU master or slave mode, the 1769‑SM2 can communicate with any third‑party drive that supports standard Modbus RTU over RS‑485.
Q3: How many drives can I connect to one 1769‑SM2?
A: In multi‑drive mode, the 1769‑SM2 supports up to five PowerFlex drives over DSI, or up to 32 Modbus slave devices, depending on baud rate and network loading conditions.
Q4: What software do I need to configure the 1769‑SM2?
A: You need RSLogix 5000 or Studio 5000 Logix Designer, along with the module’s Add‑On Profile (AOP) or generic DSI/Modbus sample code, to configure communication parameters.
Q5: How do I update the firmware on the 1769‑SM2?
A: Use the ControlFLASH utility with the appropriate firmware kit downloaded from Rockwell Automation, and connect via the module’s configuration port while the controller is in program mode.
