[b]Getting Started with the Logix5000 PIDE Function Block
Getting Started with the Logix5000 PIDE Function Block
The PIDE (Enhanced PID) is an Allen Bradley Logix5000 family (ControlLogix, CompactLogix, FlexLogix, SoftLogix) function block that improves on the standard PID found in all their controllers. First impressions of this function block are quite intimidating. If you try to dive into it head first you may just end up banging your head against a wall. Many will be quite happy to stick with the tried and true PID instruction but to compete with the more advanced process control applications the PIDE boasts the following.
It uses the velocity form of the PID algorithm. This is especially useful for adaptive gains or multiloop selection.
Control of the instruction can be switched between Program and Operator modes.
Better support for cascading and ratio control.
Built in autotuner (requires extra key)
Support for different timing modes
More limiting and fault handling selections.
Still interested? What we want to do here is basically get you off the ground with the PIDE, distill all the options to the essentials and get it working.
The PIDE is only available as a function block (sorry, no ladder). Like the PID instruction it is best to set it up in its own periodic task. The period of the task automatically becomes the sample rate (DeltaT) of the PID loop. Just make sure when adding the new routine to the task to select the Type as "Function Block Diagram."
Adding the PIDE Function Block
The PIDE instruction can be added from the Instruction Toolbar under the Process tab.
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