Allen Bradley PLC and DeltaV PK Controllers – Friends??

Friends? Probably not, but we’re pretty good making them play nice on a GMP factory floor. We just wrapped up a project where FactoryTalk took the supervisory role and now we’re flipping over to a DeltaV system that interfaces with Rockwell components.

It’s tough, but totally doable—especially in systems where data is king. Having robust and resilient communication protocols is crucial for maintaining data integrity.

In the system we just completed, we were pulling process and alarm data from a couple of single-use bioreactors. The protocol of choice was OPC UA, with FactoryTalk connecting to the DeltaV application server (configured as the OPC server).

The real trick? Licensing. Every OPC tag counted—whether it was for process values, alarms, or setpoints. For example, one critical process instrument (like temp or pH) could use up to five OPC tags for PV, alarm H, HH, L, and LL.

An option to streamline by taking just the PV, feeding it into an FT PlantPax object, and just deriving those alarms would use just one OPC tag.

The trade-off? Lower licensing costs on the DeltaV side, but potential issues with alarm log coherency.

By deriving tags in PlantPax, all alarms would announce, acknowledge, clear, and enter the audit trail seamlessly—except the acknowledgment would stay local to the FT system, potentially causing mismatches between FT View HMIs and local DeltaV HMIs.

You could create one OPC tag for an acknowledge-all function, but that opens up a new can of worms with 21CFR11 and individual attribution.

In this case, we solved it by maintaining the alarm functions at the edge in DeltaV and reconciling the alarm and event logs in the FactoryTalk system. The result? A system that lowers licensing costs, maintains GMP data integrity, and can be easily managed by local engineers.

Can’t wait to see what challenges we’ll face next as we go the other way.

If you’re considering integrating common life science automation platforms under one unified system, let’s talk!