PID Loop RS Logix 500 Remote Min/Max

I have a client that is asking to control the minimum and maximum speed of a 2 HP VFD controlled motor. Yes, it can be done on the VFD itself, but that is not what they want. They want to do it from the HMI.

in program see file I/O starting on rung number 0026.

How do I write a value to the word locations for those parameters in my PID loop? What address do I use? Easy as pie in Direct Logic that I've used for years. This is new to me.

Better to write values to the setpoint min/max or output min/max?

Go to the AB website literature library and download the instruction set reference manual for Logix500. If you are using a Micrologix then get the ISR manual for MicroLogix. In the manual you will find the block offset address for the PID min/max for SLC PLCs which use an N word block for PIDs. If its a Micrologix then the ISR will have the element designator for the PD file used for PIDs.

I suggest you have the HMI write the operator entered limits to any N word address you choose, then perform a range check to keep the operator entered values in range, then use a MOV to move the values the correct registers in the PID block.

it is a micrologix 1500. Thank you for the tip. I like the range verification check.

so in summary it is possible to do what I want once I get educated on the addresses needed?