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Get SFC condition from DB

Created by: JSMTek at: 1/16/2009 10:56 AM (4 Replies)

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1/16/2009 10:56 AM	Rate (0)
JSMTek Posts: 50 Rating: (2)	Hello! I have a DB with some REAL values (wich are set from WinCC). In my SFC i need to use these values in my SFC conditions, but I am not able to browse to the DB. I found an example (Entry ID:2860291) se below. I am not sure if I did this correctly. But i created a new CFC and added some DW_R converters, and connected theinput to theitem in the DB. (I had to change the datatypes in the DB from REAL to DWORD) Now i could browseand select the DW_R outputpinsinSFC. But when testing my SFC, my sequence completed immedeately without waiting for thecondtitions to be furfilled. I works perfectly when i use "hard coded"values in the conditions. I Opened the CFC and switched to "online" view. I could see that the inputs of the DW_R was correct,but on the output pins itdisplayed +0.0 Does anyone have a suggestion how to read DB values in SFC? Entry ID:2860291 QUESTION: In the SFC, how can I access an element of a global data block? ANSWER: You are using PCS 7 V5 and want to create a number of limiting values as real numbers in a data block. In a transition condition you want to compare a measured value with an element of the data block. For this, in the SFC you must access an element of a global data block. But it is not possible to access a real value in the DB directly in the SFC. Proceed as follows to enable this: In the DB1 create a real value (DB1.DBD0). Add a DW-R converter in the CFC chart. Interconnect the DB1.DD0 to the input of this converter. Now in the SFC chart you can access the real output of the converter using Browse.
JSMTek Posts: 50 Rating: (2)
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1/16/2009 11:57 AM	Rate (2)
CBo Gold Member Joined: 4/5/2006 Last visit: 10/10/2024 Posts: 917 Rating: (63)	Hi JSMTek, I looked into my old project developed with PCS7 v5.2.....I written a custome block to convert DobleWord To Real because function coming from library didn't work. (this function copy DoubleWord in Real wihout format conversion ) The code is very simple, create an STL Function for conversio: FUNCTION... ... L "DW Input parameter" DTR T "Real Output parameter" .... END FUNCTION About SFC browsing: Did you tryed to do as follow to put DataBlock elemt into SFC step/conditon? - open DataBlock editor in a side of monitor - open SFC editor in other side of monitor (keep open both windows make easier) - open SFC step/transition editor and write "DB Nr." (without brachet and follow with "." (dot) -in DB editor copy name element of Real/DW youneed and past in SFC editor after "." - save and compile Should be works Regards

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1/16/2009 2:08 PM	Rate (0)
JSMTek Posts: 50 Rating: (2)	Thank you CBo! This was exactly what I was looking for. It worked perfectly. It is always the simplest problems one have to struggle the most with
JSMTek Posts: 50 Rating: (2)
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10/4/2018 9:15 AM	Rate (0)
Bhairava Experienced Member Joined: 6/2/2010 Last visit: 7/26/2023 Posts: 29 Rating: (2)	How can we fulfill similar requirement in SFC type ?

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10/4/2018 3:17 PM	Rate (1)
GeronimoDK Posts: 15 Rating: (1)	Bhairava How can we fulfill similar requirement in SFC type ? Create an input of the correct data type and use this input as your condition in your SFC type. Insert SFC type in a CFC. In your CFC, connect the input of your SFC type to your DB.
GeronimoDK Posts: 15 Rating: (1)
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