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ISTACK of CPU928A

Created by: Berno09 at: 8/16/2011 10:12 AM (7 Replies)

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8/16/2011 10:12 AM	Rate (0)
Berno09 Posts: 40 Rating: (1)	dear Experts, I'm facing a problem on CPU 928A (6ES5928-3UA21), where it is going to stop suddenly several times per day.to put it back back inot "RUN", we justactivate the switch stop/run, then it works allOK. the problem isoccuringsometimes every 10 minutes and sometimes it happened once per day. I have attached the ISTACK and BSTACK, and I would appreciate your help in this matter. is it a hardware or software problem? does this CPU has internally a RAM module? regards, Attachment ISTACK CPU 928A.pdf (397 Downloads)
Berno09 Posts: 40 Rating: (1)
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8/16/2011 10:39 AM	Rate (0)
BeVee Gold Member Joined: 7/18/2011 Last visit: 10/9/2023 Posts: 521 Rating: (91)	Hi Berno, It looks like the maximum cyclus time is exceeded. This can be caused by defective hardware. Defective hardware can cause software to invoke additional error routines. Remedies Check installation for defective hardware (IO cards) Try reducing overall cyclus time by software adaptations Increase watchdog for maximum cyclus time Retrigger cyclustime during program execution. Take a closer look to FB88, maybe program get stuck in endless loop Kind regards, BV

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8/16/2011 7:44 PM	Rate (0)
Berno09 Posts: 40 Rating: (1)	many thank for your reply. I'm new in S5 PLC,I used to work on Step 7 for couple of years. In my case,I have 3 different racks and 25 input and output modules (digital and analog). how canI identifly which module is faulty? I can not change the program and download it because I have an EPROM and there is not RAM inserted in the CPU. most of the time, the CPU fault wasZYK which is the cycle time exceeded, while twice it gave me QVZ which is related to transfer of data from I/O cards. but how can I know which card is causing this problem? the ISTACK took me to the OB24 only. how can I monitor the cyclic time soI can seewith which input of output the problem begin? Regards,
Berno09 Posts: 40 Rating: (1)
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8/16/2011 8:55 PM	Rate (0)
BeVee Gold Member Joined: 7/18/2011 Last visit: 10/9/2023 Posts: 521 Rating: (91)	Berno09 many thank for your reply. I'm new in S5 PLC,I used to work on Step 7 for couple of years. In my case,I have 3 different racks and 25 input and output modules (digital and analog). how canI identifly which module is faulty? I can not change the program and download it because I have an EPROM and there is not RAM inserted in the CPU. most of the time, the CPU fault wasZYK which is the cycle time exceeded, while twice it gave me QVZ which is related to transfer of data from I/O cards. but how can I know which card is causing this problem? the ISTACK took me to the OB24 only. how can I monitor the cyclic time soI can seewith which input of output the problem begin? Regards, Hi, It's a bit tricky to diagnose the hardware if you can't change program to add some diagnostic code. You could start check connections between different racks to see if you see something abnormal. Measuring supply voltage on different IO card can help too. You could also check IO in variable table and compare what you get there with LEDs on IO cards If there are profibus IM cards.like IM308C, problem might by lost of DP station too. Any BF ledlit on those IM's ? There is no standard way to check cycle time in S5. Usually theprogrammer has to foresee some code to test cycle time. You'll have to check program code if there is a special tool available to test cycle time. Cycle time is available in system data, but monitoring these words is not possible in variable table. Check manual of 928A to find out which system data words has to be checked to read cycle time. Check error OB's , maybe there is some code foreseen to make diagnose easier. Hope this can help a bit, BV

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8/17/2011 6:46 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 10/11/2024 Posts: 3024 Rating: (1054)	Hello Berno09 Berno09 I can not change the program and download it because I have an EPROM and there is not RAM inserted in the CPU. Your single Slot 928A CPU (6ES5928-3UA21) has 64KB of inbuilt RAM (plus 46KB of dedicated DB RAM). I suggestyou do the folwloing: 1.) Put the CPU into Stop 2.) Upload the whole program 3.) Power off the PLC 4.) Remove EPROM from CPU (leave slot empty) 5.) Power PLC up 6.) Download theonline backup into it 7.) Test that all still works as before If so, you are now in a position to add some capture code into your program NOTE: Make sure you have a backup battery in your S5 power supply, otherwise you'll loose your program if a power failure happens. Berno09 most of the time, the CPU fault wasZYK which is the cycle time exceeded, while twice it gave me QVZ which is related to transfer of data from I/O cards. but how can I know which card is causing this problem? the ISTACK took me to the OB24 only. To start with see chapter 5.6.4 of the AG S5-135U CPU 928 Programming Guide to get the background and error codes reference info. Thereafter, do the following: 1.)Find an freeDB and create at least DW 0-3 in it (all of type KH is fine). 2.)Findafree FB andadd the following code to it: C DBxyz // open DB TDD 0 // accu1--> DD0 TAK // swap accu1 and 2 TDD2 // accu1--> DD2 TAK // restore accu content (in case its used elswehere in OB) BE 3.) Add the call of this FB to OB24as the first call in it 4.) When the next CPU Stop happens, open DB xyz onlineand compare the values in DW0-3 with the ones listed in the manual to identify the I/O error cause. Other things to bear in mind: If OB24 does NOT yet exist in the CPU, add a STP commandas the last line to it when you create it to ensure the CPU continues to go to STOP upon its call (see chapter 5.4 of the manual). DX 0 is used to set up general systembehaviour (e.g. max allowed cycle time)and also what OB leads to a STOP if not programmed (see chapter 7 of the manual). The S5-135U/155U CPU 928/CPU 928B/CPU 948 List of Operations manual may come in handy too. I hope this helps and pelase let us know what you find.
	Last edited by: fritz at: 8/17/2011 6:59 AM fixed manual link Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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8/17/2011 11:23 AM	Rate (0)
Berno09 Posts: 40 Rating: (1)	dear Fritz, many thanks for your help. I followed your instruction, uploaded the program and when I tried to re-download it, itgave me a message "memory in CPU not adequate", andI couldn't download the program! in addition, all fault happened today were all related to the ZYK, no one was QVZ. however,I wrote down how theOB23 and OB24 are programmed. OB23 NETWORK 1 :A DB 5 :UN D 0.1 :S D 0.1 :STP :BE ----------------------------------------------------------- OB24 :A DB 5 :UN D 0.2 :S D 0.2 :STP :BE ----------------------------------------------------------- DB5 0: KM=00000000 00000010; DW0, BIT0=1 STOP UEBER OB19 1: KM=00000000 00000000; DW0, BIT1=1 STOP UEBER OB23 2: KM=00000000 00000000; DW0, BIT2=1 STOP UEBER OB24 ----------------------------------------------------------- Regards.
Berno09 Posts: 40 Rating: (1)
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8/17/2011 5:39 PM	Rate (0)
BeVee Gold Member Joined: 7/18/2011 Last visit: 10/9/2023 Posts: 521 Rating: (91)	Hi Berno You could try this: Since you already made an upload of the program, you can safely give PLC overall reset either by PG or with switches on PLC. Download all PB,FB,FX,SB and OB's (all blocks except data blocks) Once this is done start downloading DB's and DX This forces the datablocks to be stored in memory dedicated for datablocks if normally memory is not adequate. Hope this helps a bit, good luck, BV
	Last edited by: BeVee at: 8/18/2011 2:40 PM
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8/19/2011 10:39 AM	Rate (0)
Berno09 Posts: 40 Rating: (1)	many thanks for your help Bevee and Fritz. i followed your instructions, removed the EPROM, downloaded the program as you mentioned, which gave me successfully completed. though the PLC didn't run, the stop lit was slowly blinking. i did a cold restart as the manual said, yet nothing happened. i repeated twice this action since the begining, without success. i retunred the EPROM and everything went OK as it was previously. one question, if i made the changes you mentioned in the OB23 and OB24, without removing the EPROM, does it work? another question, i tried to open the DB5 online and i couldn't. i could enter it while i"m offline. is that normal? Regards,
Berno09 Posts: 40 Rating: (1)
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