Description
Product Introduction & Engineering Value
When an AC 800M controller stops responding, the impact extends well beyond a single cabinet. Communication, control execution, and field I/O processing can all be interrupted simultaneously. The ABB PM856AK01 is designed to provide dependable controller performance for medium-sized process automation applications within the ABB System 800xA platform.
As a member of the AC 800M controller family, the PM856AK01 combines deterministic control execution with integrated Ethernet networking and flexible expansion through communication and I/O modules. It is commonly deployed in continuous-process industries where maintaining compatibility with existing System 800xA infrastructure is a priority.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | ABB |
| Model | PM856AK01 |
| Article Number | 3BSE066490R1 |
| Product Type | AC 800M CPU Controller |
| Processor | Motorola MPC860, 24 MHz |
| Memory | 16 MB |
| Application RAM | Approximately 10.337 MB |
| Firmware Storage | 2 MB Flash PROM |
| Power Supply | 24 VDC (19.2–30 VDC) |
| Power Consumption | 180 mA typical / 300 mA maximum @ 24 VDC |
| Power Dissipation | 4.32 W typical (7.2 W maximum) |
| Ethernet Ports | 2 × RJ45, 10 Mbps IEEE 802.3 |
| Serial Ports | 2 × RJ45 RS-232C (COM3 and COM4) |
| CEX Bus Capacity | Up to 12 communication modules |
| ModuleBus Capacity | Up to 96 S800 I/O modules |
| Operating Temperature | 0°C to +55°C |
| Protection Class | IP20 |
| Mounting | DIN Rail (Slide & Lock Mechanism) |
Field Application & The “Trench” Experience
A wastewater treatment facility began reporting intermittent controller communication alarms during peak operating hours. Network diagnostics initially pointed toward Ethernet congestion, but packet captures showed no abnormal traffic.
Engineers eventually discovered that the original controller was experiencing intermittent memory-related faults after years of continuous operation. Replacing the PM856AK01 restored deterministic scan execution and eliminated sporadic communication interruptions without modifying the existing control application or I/O configuration.
Typical application scenarios include:
- Boiler combustion control in utility power plants
- Chemical reactor sequence and batch processing
- Municipal water and wastewater treatment automation
- Pulp and paper stock preparation systems
- Cement kiln process control
- PM856AK01
- PM856AK01
Transparency SOP: QA & Testing
Every New Surplus or professionally Refurbished completes a documented inspection before shipment.
- Verify article number (3BSE066490R1), serial number, and hardware revision.
- Inspect CPU board, CompactFlash interface, RJ45 ports, and PCB assemblies.
- Perform power-up diagnostics using an AC 800M test platform.
- Verify Ethernet communication on both network ports.
- Test serial communication interfaces (COM3 and COM4).
- Confirm memory integrity, controller initialization, and LED diagnostics.
- Package in anti-static materials with complete traceability documentation.
The Veteran’s Tech Trap Guide
⚠️ Don’t assume every CPU fault originates from the controller. A defective 24 VDC power supply or overloaded ModuleBus can produce watchdog alarms that resemble processor failures.
⚠️ Always verify the TP830 baseplate. The stores its hardware identity through the controller baseplate. Replacing only the CPU without inspecting the baseplate connectors may leave intermittent communication problems unresolved.
PRO TIP: Before replacing the controller, perform a complete backup of the Control Builder project, firmware revision, IP configuration, and application database. Restoring the software is usually more time-consuming than replacing the hardware.
PRO TIP: Inspect every Ethernet connector inside the cabinet. Loose RJ45 locking tabs and oxidized contacts frequently cause communication faults that appear to be CPU failures.
Dynamic FAQ
Q1. What is the primary function of the ABB ?
The is an AC 800M controller that executes process control programs, manages communication networks, and coordinates distributed I/O within ABB System 800xA automation systems.
Q2. How many I/O modules can one support?
The controller supports up to 96 S800 I/O modules on the ModuleBus, depending on the overall system architecture and installed communication modules.
Q3. Does the include Ethernet communication?
Yes. The controller provides two integrated RJ45 Ethernet ports for the Control Network, in addition to two RS-232 serial ports for communication and engineering access.
Q4. Is the suitable for redundant CPU configurations?
No. The is a non-redundant AC 800M controller. Applications requiring controller redundancy should use compatible redundant AC 800M controller models.
Q5. How is New Surplus authenticity verified?
Each controller is verified for article number, hardware revision, PCB integrity, communication functionality, memory operation, and successful startup in a compatible AC 800M test environment before shipment.
Q6. What warranty is typically available?
Warranty terms vary by supplier. Most industrial automation distributors provide a functional warranty for New Surplus and professionally refurbished controllers after documented inspection and operational testing.
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