Hello All.

Is it possible to have 2 Process variables for the same PID in S7 1200?

2 Process variables along with their respective Setpoints .for single PID?

GaJEnDrA D S

Hello All.

Is it possible to have 2 Process variables for the same PID in S7 1200?

2 Process variables along with their respective Setpoints .for single PID?

 Hello Gajendra DS;

It would be best if you clarify your application.

If you mean 2 Process variables with 2 Setpoints, I do not think this is possible with a single instance of PID_Compact. 

PID_Compact is basically a standard SISO PID (single input single output). If you are looking for a MIMO (multiple in, multiple out) PID, in Siemens' world you have to look at the MutiVarible Model Predictive Control blocks available only in the PCS 7 environment.

You would need multiple calls of PID_Compact in your s7-1200 program to cntrol 2 distinct outputs with their own setpoint settings.

If this is not what you are looking for, please take the time to describe what you plan to do in your project. Maybe we can offer some hints.

Hope this helps,

Daniel Chartier

dchartier

 

GaJEnDrA D S

Hello All.

Is it possible to have 2 Process variables for the same PID in S7 1200?

2 Process variables along with their respective Setpoints .for single PID?

 Hello Gajendra DS;

It would be best if you clarify your application.

If you mean 2 Process variables with 2 Setpoints, I do not think this is possible with a single instance of PID_Compact. 

PID_Compact is basically a standard SISO PID (single input single output). If you are looking for a MIMO (multiple in, multiple out) PID, in Siemens' world you have to look at the MutiVarible Model Predictive Control blocks available only in the PCS 7 environment.

You would need multiple calls of PID_Compact in your s7-1200 program to cntrol 2 distinct outputs with their own setpoint settings.

If this is not what you are looking for, please take the time to describe what you plan to do in your project. Maybe we can offer some hints.

Hope this helps,

Daniel Chartier

 Hi,

Thank you for your valuable response.

I have said clearly what is my requirement - MIMO . 

I hope I can use PD portion of SISO - PID . I also tested its working. I am looking for your hints. As you cant completely bypass I parameter as it gets stuck for condition where error remains stagnant. I'm using optimum, negligible I parameter but basically its a PD Controller. 

My understanding - Once the setpoint and control variable changes it starts from present to future as I is set to be negligible.. So I also apparently works from present until next swapping for control variable along with its setpoint with minimum offset from previous variables. 

For example 

P - 100

I - 5

D - 500 

Also my system doesnt need sharp tuning  or control as the my application is very large one.

dchartier

 Can You Pls Help understand what is Process value limits, Process value scaling? Im not able to find it from help. 

My sensor range is 【-20，60】

what should be the entry in above 2 settings?

Regards

Gajendra D S.

GaJEnDrA D S

 

dchartier

 Can You Pls Help understand what is Process value limits, Process value scaling? Im not able to find it from help. 

My sensor range is 【-20，60】

what should be the entry in above 2 settings?

Regards

Gajendra D S.

 Hello. Somebody here pls ?

Hello GajendraDS;

The best explanation for PID_Compact (V2) ca be found in the Step 7 v16 system manual:

- Process value scaling:

https://support.industry.siemens.com/cs/ww/en/view/109773506/42099485323

- Process value limits:

https://support.industry.siemens.com/cs/ww/en/view/109773506/43310534923

Look up PID_Compact descriptons in the navigation column of the system manual, you should find most of your requirements.

Hope this helps,

Daniel Chartier