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TEMP variable and STAT variable

Created by: peters at: 9/2/2006 7:27 AM (13 Replies)

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9/2/2006 7:27 AM	Rate (0)
peters Posts: 122 Rating: (4)	[:o]dear experts: what is the difference between "TEMP variable" and" STAT variable" declared in the "Variable declaration table" in S7?thanks!
peters Posts: 122 Rating: (4)
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9/2/2006 10:36 PM	Rate (1)
Thijs Posts: 121 Rating: (16)	Temp vars in the L# stack. It's only used in the call off the FC/FB. The data is non retentive (lost after end of the function) STAT vars are stored in the corresponding DB (STATS are only in FB's) TEMP are in FC's and FB's
Thijs Posts: 121 Rating: (16)
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9/3/2006 2:29 PM	Rate (9)
Late Platinum Expert Joined: 1/7/2006 Last visit: 11/17/2023 Posts: 2705 Rating: (318)	Hi Peters, The TEMP are on temporarely local data and are not initialized when you came in the FC or FB! This data can't be used to hold data, only internally in the block. The STAT are data that is initialized when you use them in the FB with the last data that is written in it with the last call. Those data is "saved" when you leave the FB, when you use a FB then please useSTATs instead of TEMPs. Please consider also the IN, OUT and INOUT parameters on a FC/FB! The IN is not that difficult, but the OUT and the INOUT are not that easy to understand. An OUT is only for OUT-coing information, and is not read in the next time you made a call to the FB/FC!! An INOUT reads in the last information and have the status of the last call.
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
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9/4/2006 3:29 PM	Rate (1)
peters Posts: 122 Rating: (4)	so clear,so good,thanks very much!
peters Posts: 122 Rating: (4)
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4/25/2012 7:47 AM	Rate (0)
Amoralis Posts: 46 Rating: (5)	Hello, Late! It was clear for me all the time, but recently I noticed thatbehavior ofTEMP variables inOB1 is different. It looks like additional TEMPs (more than already there) in OB1 remains their values between calls. I was really surprised. Seems like all FCs and FBs have the same L memory for all, andOB1 have different L memory. May be it depends on calling structure... Could You please point me out a documentation where this is explained? Thank You a lot!
Amoralis Posts: 46 Rating: (5)
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4/25/2012 7:59 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	Amoralis ...It looks like additional TEMPs (more than already there) in OB1 remains their values between calls.... .... NO! that is only coincidence!
IBN-Service Posts: 8946 Rating: (999)
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4/25/2012 8:08 AM	Rate (0)
Amoralis Posts: 46 Rating: (5)	Hello,IBN-Service! If so, could You please explain OB1 NW1 of MODBUS_TCP_CP_Redundant example from SIEMENS? It works fine in OB1 (not as in FC/FB)! Attachment 2012-04-25_121346.gif (1911 Downloads)
Amoralis Posts: 46 Rating: (5)	Last edited by: Amoralis at: 4/25/2012 8:18 AM
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4/25/2012 9:03 AM	Rate (0)
Aret Posts: 2348 Rating: (264)	Can't see the problem. Actually OB1 has 20 bytes of TEMP info. So vars defined by user should start at 20.0. If you use it inside FB please move front defining variables to stat area. If you use FC - use DB/M area for example.
Aret Posts: 2348 Rating: (264)
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4/25/2012 10:29 AM	Rate (0)
Amoralis Posts: 46 Rating: (5)	Hello, Aret! Thank You for your assistance! I am sorry if I not clearly explained the situation.I know how to use edge detection correctly, and I know that it is not correct to use L stack for this in FC and FB. I also belive that person from SIEMENS who have written this example know what he or she doing, when using L stack for this in OB1. So I just whant to know why using L stack in OB1 for holding data for FP operator is correct in OB1.
Amoralis Posts: 46 Rating: (5)
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4/25/2012 11:44 AM	Rate (1)
Aret Posts: 2348 Rating: (264)	Well, it can be explained - on using TEMP variable inside OB1 L20 byte is marked as used and all following FC/FB calls would use local stack from 21th byte (or 22th). So generally they would have no access to L20 byte (the only way they CAN do it - using pointer on P#V area, but it's very rare case). As there is no forced cleaning of local data variables, defined as in example you provide, variables WOULD retain it's value from cycle to cycle, though i can't say it's elegant design.
Aret Posts: 2348 Rating: (264)	Last edited by: Aret at: 4/25/2012 11:46 AM
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