Pump PLC Program (RS500)

[Freak]

Hi All,
I have a RS500 program for a wine pump. In manual the pump is running too fast and I need to slow it down, sounds pretty easy. PLC talks to a touchscreen that provides a setpoint for the speed reference (N7:0), for some reason teh PLC then multiplies this by 164 to then create teh speed reference. In auto the PLC gets a signal from a level probe that it then divides by 164.
I am assuing I need to modify the manual multiplication factor but I am curious as to how they got the 164 and I don't really want to play with this unless I now why this number.

Any ideas would be appreciated.

Cheers
Peter

 

[Ken Moore]

In auto a PID instruction is outputting a raw count of 0-16383, they then scale the output before sending to the VFD. When in manual, you enter a value from 0-100%, instead of scaling they just multiply by 164, to get you in the same ball park as the PID output. It's not the way I would have done it, but it should work. If the pump is running to fast, perhaps your setpoint is too high.


Ken

 

[Freak]

Thanks Ken - that makes sense, for some reason I simply couldn't see why it was 164 now I know!

Cheers
Peter