My first PID in ABradley

Hi all,

...because in life there's always a first time for everything here it comes my first time for programming a PID

I've read and studied on many resources, literature and ABradley official documentation...but yet never programmed for real a PID so all your tips will be welcome.

The case is next: A tank with water that must be pumped out. Two bombs: One is linked to a speeddrive and the other is started normally (electroniclly, using a SIRIUS siemens 3RA6 electronic starter). We have also two swtiches,one for high level and other for low level.

We also have a LIT (Level transmitter giving an analogic signal 4-20 that will be scaled to an output so that monitoring the water linelevel)

Conditions:

If LSL=0 (and therefore HSL=0 too) none of the pumps will be started up.

If LSL=1 and HSL=0 (medium level) the pump with the speedrive will try to keep the water level in a constant value (Setpoint) determined via SCADA. The setpoint will be inside a range of tolerable error (between high and low alarms). Here my PID will be operative.

If LSL=1 and HSL=1 both pumps will work.

As soon as the level returns to the setpoint the second pump (the one without speedrive) will stop.

It's not a difficult programmation but still I haven't ever truly used the PID function in AB (I'll use a 1769-L32E in this project) and I get a bit of mess when trying to find out what parametres in the middle of the whole set of the PID function paremetres, are the ones I have to use exclusively. I would aprecciate any clues about this.
Thanks in advance.

Ruben:

This is one of my PID, I use operator mode, i like it because is the easiest one, you can change SPoper, CVoper,Opermanreq, and Operautoreq thru hmi, in my case I use a PV700+.

today I've decided to go one step beyond on my first PID programmation and after reading the tips give by Widelto, I've got the courage enough to open the properties window of the PIDE block ....and have say I've become overwhelmed at first sight with the "General Configuration" tab.

Here some doubts about it (since I haven't found quite usefull the online documentation provided in RSLogix)...

1)The timing mode...what should be the more suitable option for my application (described above)?...My application doesnt need an extreme accuracy since it's not dealing with a very critical process....The only point at which I would need more accuracy is the regarding one to the flowmeters, but in this PID I'll set them aside by now.

2)Equation type: Independent or Dependent?

3)Zero crossing Deadband....Not sure to have understood this concept.

4) Override value...derivative smoothing

Surely I don't have to tweak on all parametres of the PIDE as seing the example given by Widelto in which few of them are displayed and it is an easy working model....though as this is my first time programming a PID I don't know for my particular case what ones should I adjust and what ones I don't need.

Any ideas?
Thanks.