When Two PLC Worlds Must Meet
Modern plants often run ABB AC800M for process skids and Allen-Bradley ControlLogix for packaging or material handling. These two systems must share setpoints, status words, and alarms. EtherNet/IP is the common language.
First, both controllers speak CIP over Ethernet. Second, the Allen-Bradley side can act as an EtherNet/IP scanner. Therefore, the ABB AC800M can present data as an EtherNet/IP adapter. This avoids expensive protocol converters.
Step 1: Design the Ethernet Network
Use a dedicated industrial Ethernet VLAN. Assign static IP addresses to both controllers. A typical layout looks like this:
- Allen-Bradley ControlLogix: 192.168.50.10
- ABB AC800M CI873 module: 192.168.50.20
- Subnet mask: 255.255.255.0
- Engineering station: 192.168.50.100
Moreover, disable unused Ethernet ports on switches. Use managed switches with IGMP snooping if multicast CIP connections are planned. Finally, verify both devices can ping each other before moving to controller configuration.
Step 2: Configure ABB AC800M as Adapter
In ABB Control Builder, add the CI873 EtherNet/IP adapter module to the AC800M hardware tree. Set the IP address and module identity. Enable the adapter instance for the required assembly objects.
Map internal AC800M variables to EtherNet/IP assembly instances. For example:
- Assembly 100: Output data from ABB to Allen-Bradley
- Assembly 150: Input data from Allen-Bradley to ABB
However, data size must match the scanner configuration exactly. A mismatch of even one byte breaks the connection. Therefore, document byte counts and data types carefully.
Step 3: Configure ControlLogix Scanner
Open Studio 5000 / RSLogix 5000. Add a Generic Ethernet Module to the I/O tree. Enter the AC800M IP address and communication format: Data - INT.
Define the scanner assembly sizes to match the ABB adapter. Set the requested packet interval to 10 ms or 20 ms depending on process speed. Enable ownership type "None" if other scanners also need the adapter data.
Step 4: Map Tags and Test
In ControlLogix, create controller tags linked to the generic module I/O. In AC800M, use those values in function block diagrams or structured text. Test the connection with simple toggle bits first.
- Toggle a bit from Allen-Bradley and confirm it arrives in AC800M.
- Write a heartbeat counter from AC800M and verify it increments in ControlLogix.
- Add real process tags once basic handshake works.
Finally, monitor module status LEDs and connection faults. A flashing red NET light usually means configuration mismatch or cable fault.
Conclusion & Action Advice
Integrating ABB AC800M with Allen-Bradley ControlLogix over EtherNet/IP is cost-effective when both sides use correct assembly sizes and matching data types. Plan the network carefully, configure the AC800M adapter precisely, and test with heartbeat tags before handing over to operations. Document the tag map to simplify future maintenance.