Honeywell 2MLL-CH2A Serial Communication Interface Module

The Honeywell 2MLL-CH2A is a dual-channel serial communication interface module designed for MasterLogic-200 PLC systems. It incorporates one RS-232C port and one RS-422/485 port, enabling versatile data exchange between the controller and external hardware such as HMIs, programming PCs, modems, and field instruments.

Interface Performance and Network Topology

The module features two independent communication interfaces: an RS-232C channel supporting point-to-point connections up to 15 m, and an RS-422/485 channel supporting multi-drop networks up to 500 m. Configurable baud rates span from 300 bps up to 115,200 bps.

Operation supports both Server mode and P2P (Client) mode across Modbus RTU/ASCII (Master/Slave) protocols, as well as user-defined proprietary protocols. Network station numbering ranges from 0 to 31, accommodating up to 32 addressable stations on a serial bus.

Setup and Module Diagnostics

Module configuration and link definitions are managed using SoftMaster-NM software. Diagnostics include auto-scan, frame monitoring, link status tracking, and internal loop-back testing to verify hardware signal paths.

Front-panel LED indicators display operational status for RUN, I/F, TX, RX, and ERR. The unit consumes approximately 310 mA at 5 VDC from the backplane supply.

Technical Specifications

Frequently Asked Questions

Q: What maximum transmission distance is supported on each serial channel?

A: The RS-232C channel supports distances up to 15 m, while the RS-422/485 channel supports cable runs up to 500 m.

Q: Which communication protocols can be configured on the 2MLL-CH2A module?

A: It supports Modbus RTU and ASCII in both Master and Slave roles, as well as custom user-defined proprietary protocols.

Q: How many station addresses can be configured on the RS-422/485 multi-drop network?

A: Station numbers can be set from 0 to 31, supporting up to 32 active stations on the bus.