1/4/2013 5:52 PM | |
Joined: 4/22/2010 Last visit: 5/3/2024 Posts: 5697 Rating: (715) |
Hello, Can you please attach a printsreen or a PDF off your FB 41 Block call? You could allso have a look at Hdhosseini example Here If used right no scaling is needed, you can connect the PID directly to an output. You should use the PID output LMN-PER to connect directly to analog output. Regards, Marcjan |
Last edited by: Marcjan at: 1/4/2013 5:59 PMProblem solved? |
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1/4/2013 6:16 PM | |
Posts: 4 Rating: (0) |
Thank you so much for your quick respons! :D Here's a PDF file of the block, the input called "Motstand" means a Potentiometer AttachmentContC.pdf (250 Downloads) |
1/4/2013 6:20 PM | |
Joined: 9/27/2006 Last visit: 9/20/2024 Posts: 12282 Rating: (2684) |
Hello EE; Would you mind giving us the information on addressing and range you have selected, simply so we can validate the data? As you can see from the attached file, the analog output adrresses of the integrated IO on a CPU 314C-2PTP or CPU314C-2DPstart at PQW752.(channel 0) and PQW754 (channel 1) Note, the addresses of analog outputs for a CPU314C-2PN/DP are PQW800 (Channel 0) and PQW802 (Channel 1). You must also enter the correct parameters for the type and range of analog output signals in HWConfig as shown in the same document. The information is extracted from the following manual: CPU 31xC and 31x Technical Specifications If this has been done correctly, and you still need a scaling block, look in the TI-S7 conversionlibrary for FC 106 "Unscale" that will take as an input parameter a numerical value (in REAL format, such as 0.0 to 100.0) and send out an integerdecimal value 0-27648 that the analog output can transfer to 0-20mA, 4-20 mA... Use the F1 key to open the online help function for details on the function. Hope this helps, Daniel Chartier Edit: I have just opened your pdf file, and I notice a few things you should look into, because your PID block cannot function as it is programmed (which explains why you have not output signal): The COM_RST (complete reset) variable parameter needs to be active once at the start of the CPU to ;launch the SFB 41, and the loop is by default in manual mode (you have to set an inut variable MAN-ON to 0). For the treatment of COM_RST, I suggest you SETCOM_RST in OB100 (so the variable is active before your other OBs are called) and then RESET in the networf following the SFB 41 call, in OB 35. You have not tuned your loop, what Gain and Time values are you goind to use to control the output, eg. GAIN, TI, TD (and the enabling bits P_SEL, I_SEL,D_SEL...) The LMN_PER variable should point to a valid address for your analog output, What does the symbol "I/Pcoverter" show? For more details, have a look at the following FAQs: What should you watch out for when calling and assigning parameters to the controller functions in function blocks (S)FB41, (S)FB42 and (S)FB43? Where can you find descriptions and examples of PID control with FB 41, FB 42 and FB 43, and SFB 41, SFB 42 and SFB 43? D.C. |
Last edited by: dchartier at: 1/4/2013 6:39 PM |
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1/4/2013 6:45 PM | |
Posts: 4 Rating: (0) |
Love the great respons guys, here's a print out of the HWconfig. I think i've done it as you saydchartier, but I can't figure out how to get the manipulated value into the unscaling block, do you use an MD? AttachmentHWconfig.pdf (190 Downloads) |
1/5/2013 10:12 AM | |
Posts: 4 Rating: (0) |
Sorry for the late updated i think there's a time diffrence here :D So i tried setting the COM_RST in OB100, but the operation is illegal :S Explenation of pictures: - The black graph you see is the setpoint value, it's adjusted with an Potentiometer, named: "Motstand" in program. - The blue graph is the analog output given from the PLC, it's hardwired to an I/P-converter, named: I/Pconverter in program. - The red graph is the prosess value given to the PLC by an analog input, It's hardwired to an Rosemount pressuretransmitter. Named: "99PT0001" in the program.
I don't want to upload the program because i want to understand the program and how it's built up. I think it's best for the learning process to actually interact with it firsthand. AttachmentPictures.zip (172 Downloads) |
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