Cascade loop in manual mode

Hi there,

I would like to know how I can set the output of my PID cascade loop to zero as soon as it goes to manual. That's just for the safety. Also I would like to be able to give it different setpoint in manual mode and run it. The problem is that if I tell it to set it's output to zero in manual mode then I wouldn't be able to give it different set points and operate it in manual mode.

Regards

This is a simplistic way of doing it

Post the output of the PID into a register (say R1). Use this register to post the value to the analog output.
An auto contact should be in the rung before the PID instruction

Now have your mnanual mode below the auto PID, and use HMI values to write into the register R1 using a move instruction.

Depending on your PLC many have Manual mode built into them

Cheers