Problem:
The client needed to communicate on the latest Allen Bradley PLC family of processors; ControlLogix 5590, Logix SIS (Process Safety), CompactLogix, and MicroLogix controllers. All of these communicate over Ethernet. The current VAX application, which was on DEC servers, KF2 Modules, and VAX/PLC Data Highway, communicated over RS-232 serial communication.
The Challenge:
- Aging VAX hardware threatens production continuity for irreplaceable archive material.
- Serial terminal servers creating single points of failure.
- Inability to integrate with modern workflow management systems.
Action:
Salem Automation modified COTS ABNET software that replaced the client’s VMS 6001NET communication software. The program was compiled and executed on one of the client’s VMS nodes. With the existing VMS code, Salem and the client debugged and tested the program to allow VAX-to-PLC Ethernet communication. The client was able to send a message from the VAX to PLC5 and another message to the ControlLogix PLC through Ethernet. These test results gave our client confidence to implement the ABNET software into production.
The Solution:
- Maintained proven VMS application layer with zero code changes.
- Modernized hardware platform (vtVAX on reliable, supportable systems).
- Replaced failure-prone serial infrastructure with Ethernet.
- Created pathway for future OT/IT integration (production tracking, quality data to enterprise systems).
- Phased implementation maintained 100% uptime.
Conclusion:
When fully implemented, the application will no longer communicate over RS-232 serial communication nor rely on KF2 modules, DEC servers, and VAX/PLC Data Highway communication. Our client will be able to communicate with their current hardware. As a result, the application will be more reliable and easier to support.