FB41 Help.

duckie112

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Join Date
Mar 2012
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Hi, Im currently using the cpu315-2dp module with an analog input. On the input is a potmeter attached to and I got the assignment from my boss to make a closed loop simulation with only the potmeter and fb41. Is that possible or not? If its not please tell me. If it is then how. So far I can only test it while turning the potmeter wich results in seeing the fb41 work but thats like me being the temperature sensor...
I need a way wich the PLC act like a heater and a sensor while the potmeter is setting the SP_INT.
Please tell me if its possible or not since my boss want to see the results on a scope >.>
 
Yes it is possible.

You can start with this:
Connect a MD to the output (LMN, was it?) and use the same MD as your PV. Connect the pot to the SP. Now the controller will play, but the time constant is close to zero.

Then you must develop some code that can simulate the heating process. What kind of heater are we talking about? (On/off, or proportional, ..?)

Kalle
 
KalleOlsen said:
Yes it is possible.

You can start with this:
Connect a MD to the output (LMN, was it?) and use the same MD as your PV. Connect the pot to the SP. Now the controller will play, but the time constant is close to zero.

Then you must develop some code that can simulate the heating process. What kind of heater are we talking about? (On/off, or proportional, ..?)

Kalle
Click to expand...
I tried the loopback with the MD that youre saying but didn't knew yet about the code for the heater. The heater can be anything though on/off or proportional I don't really care since I only want to see the outputs of it on an osciloscope and then the boss decide wich 1 to use. So if there are examples for each then thanks alot =D this is something we were aiming for.
 
Last edited:
You seem like you have given up at the first hurdle. Have you read the manual for FB41?

Is FB41 located in OB35? What cycle time have you configured for OB35 and FB41

Have you made sure that the PID is not in manual- it is by default

Have you entered a GAIN value? Try and post a screenshot or similar



Cheers
 
cjd1965 said:
You seem like you have given up at the first hurdle. Have you read the manual for FB41?

Is FB41 located in OB35? What cycle time have you configured for OB35 and FB41

Have you made sure that the PID is not in manual- it is by default

Have you entered a GAIN value? Try and post a screenshot or similar



Cheers
Click to expand...
Yep, Yep, Yep and Yep. I can make the PID to work, but the thing I want is to have a fully closed loop system with a seperate heating/cooling process simulation since I cant get a nice graph out of the outputs I have now with only a potmeter. If I simulate the heating/cooling process I can get better graphs. I tried Scilab to get such screens and the boss was happy with it but he want to get the same things with a PLC and an osciloscope and a potmeter for the SP_INT. When I loop back the output to the input back now I get nothing near that. And like a poster in here said is that a simulation is possible inside the PLC. Thats kinda what I'm looking for so I can demonstrate the process without having to get the hardware for it (were kinda low budgeted)
 
OK I misunderstood what your trying to do. You want to simulate a process and drive it from FB41...correct? Do you have PLC Sim ?
 
Last edited:
Hi look at the example Zen01_13 and then in the continuous folder. There is a sample process for FB41 there.

Simatic Manager > Open > Examples Tab > Scroll down to Zen01_13

Cheers
 
cjd1965 said:
Hi look at the example Zen01_13 and then in the continuous folder. There is a sample process for FB41 there.

Simatic Manager > Open > Examples Tab > Scroll down to Zen01_13

Cheers
Click to expand...
Thank you I will look into it tomorrow on work =D its time to head home now and I like to have work and private seperated. I knew about those examples but actually never looked at it didnt expect a kind of simulation for FB41 was in there.
 
I have looked into the example but it seems they use fb58 and fb59 instead fb41 :O or is this used with fb41 for simulation or something? So far i cant make any sense out of it. Can it be used with fb41 with an analog output so I can put a osciloscope on to measure the values?
 
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