ABB PM856AK01 3BSE069514R1 AC 800M Processor Unit

The ABB PM856AK01 3BSE069514R1, also cataloged as the PM856AK01 Processor Units, operates as a dedicated hardware component for control logic execution and field I/O synchronization within ABB System 800xA networks. Operating on an MPC860 processor running at 24 MHz with 16 MB of onboard RAM, this unit coordinates deterministic field data transfer across local ModuleBus and CEX-Bus expansion modules. The hardware features two Ethernet communication channels, dual RS-232C serial ports, and an integrated CompactFlash memory interface.

Hardware Specifications

Backplane Bus Communication Velocity & I/O Scaling

The unit manages communication throughput across the internal backplane bus, transferring field device data between the processor core and attached S800 I/O modules. Operating with a configurable ModuleBus scan rate from 0 to 100 ms, the processor scales up to 96 direct I/O modules without degradation of control loop execution timing. Auxiliary communication expansion occurs through the CEX-Bus, which accommodates up to 12 communication interface units while preserving system backplane communication velocity and task scheduling determinism.

Frequently Asked Questions

Q: What is the current draw and power requirement for the module during operation?

A: The module operates on a nominal supply voltage of 24 VDC with an allowable range of 19.2 to 30 VDC. Typical current consumption is 180 mA at 24 VDC (4.32 W dissipation), reaching a maximum of 300 mA at 24 VDC (7.2 W dissipation) under full load.

Q: Can the processor unit be configured for redundant CPU operation?

A: No. The PM856AK01 hardware architecture is designed strictly as a non-redundant, non-high-integrity controller unit. It is dedicated to single CPU applications within the AC 800M system environment.

Field Installation Guidelines

Mount the processor base vertically on a standard 35 mm DIN rail inside an IP54 or higher industrial enclosure to ensure adequate heat dissipation through thermal convection. Maintain at least 50 mm of vertical clearance above and below the module housing. Connect the primary 24 VDC power conductors through shielded wiring, grounding the shield directly to the nearest low-impedance ground bar. Ensure that CEX-Bus expansion units are seated securely and locked using the retaining clips to prevent backplane contact wear from ambient mechanical vibration.