Controllogix Function Block


Thread Starter

S. Blais

I'm currently programming process control in a Controllogix. I'm using function blocks. Is there something special (and not mentioned by AB) I should know about function block? Any bugs or problems?

It is the first time I'm using Controllogix for process control. Is there any known bugs in Controllogix's PID or PIDE algorithm?

If so, please let me know!!!


S. Blais
No major problems. The biggest inconvenience is that you can't do online FB programming with the current release. You can change the block
parameters (gains, alarms, limits, etc.) online, but you can't edit the FB diagram itself. That's supposed to change with version 11 in a few months.

As far as learning curve details, make sure you understand the Prog/Oper modes that are used for several blocks, including the PIDE. Prog and Oper give two separate modes for commanding the block, so you can implement supervisory algorithms with the Prog mode. It's very handy
to hook up a test rig with your HMI of choice and play around with it to understand how it works.

I haven't seen any problems with the PIDE block. You can select either an independent or dependent form of the PID equation in the setup, and all the usual functionality is provided. It does take a good reading of the docs to understand the details. The docs aren't bad, though.