Programmable controller (Function and MATCHFLOW)

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Posts: 10
Joined: Tue Apr 09, 2019 2:55 pm

Fri May 10, 2019 1:01 pm

Good morning,

I contact you for a doubt regarding the realization of the programmable controller.
Starting from the material provided in Polysun's Tutorial_EN I created a new controller, however due to the absence of some practical examples I cannot find the error.

Starting from the attached file, I would like to have the "tube 2" temperature = 70 ° C. The "tube 39" temperature is known and fixed = 95 ° C.

The control is activated if in the "tube 38" there is a flow of fluid and at the same time the temperature in the upper part of the storage is less than 70 ° C.
In this case the "pump 3" is activated and the mass flow is obtained through the MATCHFLOW function (whose energy, necessary to bring the fluid into the "tube 2" at 70 ° C, is obtained through an auxiliary variable, as shown in attached) .

The doubts are as follows:

1) What is the correct syntax to have the two conditions coexist, avoiding the error shown in the attachment?

2) If I put only one of the two options the mass flow rate does not change (error in the MATCHFLOW?) Remaining fixed at 3600 l / h. (The pump has a controlled mass flow). The error is related to the definition of MATCHFLOW?

3) If I activate the regulation in the presence of fluid in the "Pipe 38" (I2 <> 0 or I2> 0), I note that the pump is activated even if the fluid does not actually flow in the pipe 38.

4) The auxiliary variable thus defined is calculated in relation to the values ​​recorded "an instant" before. Is it possible to obtain this instantaneous value?

I hope I can create a proper adjustment through your advice.

Thank you very much indeed because you already sent me good knowledge on the use of the software.

Best regards,
Error_IF.PNG (7.29 KiB) Viewed 16071 times
definition_power_exchanged.PNG (79.9 KiB) Viewed 16071 times
control_mass_flow_rate.PNG (80.11 KiB) Viewed 16071 times

Posts: 66
Joined: Mon Jun 18, 2018 4:01 pm

Tue May 14, 2019 11:26 am

Good morning

1. Check page 231 in the user manual for the correct syntax.
2. Might be solved with the correct syntax.
3. I would try it with only I2>0 and skip the formula I2<>0. Otherwise I have no other idea.
4. Unfortunately, you can't but it would really make a difference.

Sunny greetings

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