Overview

The ABB PM856A is a high-performance CPU module within the AC 800M controller family, engineered for advanced process control, high-availability automation, and large-scale distributed systems. It executes complex control algorithms, handles extensive I/O networks, and maintains reliable operation in demanding industrial environments such as power generation, petrochemicals, and manufacturing.

The controller consists of a CPU board with a high-speed processor, RAM memory, real-time clock, LED indicators, CompactFlash interface, and an INIT push button. The base plate provides dual Ethernet ports (CN1, CN2) for Control Network communication and two serial ports (COM3 RS-232C with modem signals and COM4 isolated), enabling flexible integration with sensors, engineering tools, and third-party devices.

Technical Data

Typical Applications

• Process industries: Supervising chemical, petrochemical, pharmaceutical, and oil & gas processes via large distributed I/O networks.

• Power generation: Controlling turbines, boilers, auxiliary systems, and excitation platforms with high reliability.

• Water treatment: Managing pumps, mixers, valves, and water quality instrumentation.

• Manufacturing automation: Coordinating production lines, machining cells, and robotics.

• Infrastructure systems: Supporting building automation, HVAC, energy management, and utilities.

Example: In a major refinery, the PM856A communicates with numerous local and remote I/O stations to monitor and control thousands of process signals across multiple production units.

FAQ

Q1: What is the ABB PM856A used for?
A1: It is a CPU controller module for the AC 800M system, responsible for executing control logic and managing communication with local and remote I/O.

Q2: How many I/O stations can it connect to?
A2: Up to 8 local I/O stations (non-redundant) and up to 98 remote Profibus DP stations.

Q3: What communication interfaces are available?
A3: Two Ethernet ports (CN1, CN2) and two serial ports (COM3 RS-232C with modem signals, COM4 isolated).

Q4: How is the PM856A installed?
A4: It mounts on a DIN-rail using a slide-and-lock mechanism for secure and tool-free installation.

Q5: Does each controller have a unique identity?
A5: Yes, each base plate includes a unique Ethernet MAC address for system identification and configuration.