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Extracting Info from the diagnostic buffer

Created by: AHWHG at: 2/16/2010 2:24 PM (4 Replies)

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2/16/2010 2:24 PM	Rate (0)
AHWHG Posts: 3 Rating: (0)	I want to extract the diagnostic buffer and LED status from the CPU and display on a third party DCS. I thought I could do this using SFC51 and SSL ID 00A0 & 0019, but I can only call SFC51 if the CPU is running. To get the "stop LED" status and to get the last entry in the diagonostic buffer I need to run SFC51 after the CPU has stopped. I thought there might be a fault OB that ran after the last scan as with other manufactures. I also thought about putting the call at the end of each fault OB80,81,82 etc but if the switch on the front of the CPU is switched to stop no OB's are run. Is there any way of doing this or getting the information from a different source. The information is obviously there as you can get the data I want on a HMI. I think the HMI uses the S Alarms or SDB's, is there any way of accessing this data and using it for a third party DCS.
AHWHG Posts: 3 Rating: (0)
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2/16/2010 3:49 PM	Rate (0)
SILOGIC Posts: 17 Rating: (0)	Dear, I don't know if there is OB that runs with CPU in stop mode or something like that, but, what comes to my mind that could help is to use a "Watchdog" or "Handshake" bit between the DCS and your remote CPU. It is, a flag bit allocated in your CPU, that while the program is runnig it puts into 1 when it detects that its value is 0, and the remote DCS put it into 0 when detects that it is 1. If whithin an elapsed time, the state of the bit doesn´t change, then you know that the communication is lost or the remote CPU is stopped. Hope it could help. Best regards, Patricio Novotny SILOGIC Ingeniería y Automatización Bolívar 284 Piso A - (B1704BKF) Ramos Mejía - Bs. As. - Argentina tel. 54 11 4656 4349 fax. 54 11 4464 5844 cel. 54 11 15 6058 0699 www.silogic.com.ar
SILOGIC Posts: 17 Rating: (0)
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2/17/2010 10:00 AM	Rate (0)
AHWHG Posts: 3 Rating: (0)	Thanks for the info, but a watchdog does not help me get the diagnostic buffer information. I need to get the fault code from the diagnostic buffer in the event of error/faults. i.e.The specification I have says the DCS will respond like this"In the event of the stop switch being activated, the run LED on the PLC mimic displayed on the DCSwill be extinguished, the stop LED illuminated and the diagnostic buffer will display the error code 4303 (HEX)". I can do the stop and run LED's from a watchdog but the only way I thinkIcan do the dianostic buffer is to use SFC51. The original job we did for this customer use a different PLC that had a fault task handler where this information could be set/read, but on this job the customers client has specified Siemens so we have done a direct conversion, everything works fine apart from this one little bit. Thanks for your help.
AHWHG Posts: 3 Rating: (0)
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2/18/2010 8:46 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 1/15/2025 Posts: 3029 Rating: (1058)	Hello AHWHG this is indeed a bit of a tricky one and all I can offer are a coupleofideas: 1.) Use the CPU's Web Server: Pre-Requisite: CPU with inbuiltWeb Server (check in HWconfig if you have a "Web" tab in the properties of your CPU). All you have left to do now is to call a Web Browser on your DCS in case the CPU goes to Stop to"visualise" the CPU's Diagnostic Buffer on the DCS (you could even embedd a Web Broswer active X control intoa screen of your DCS and call up this screen). Don't know if this is an acceptable solutionfor you though (this will NOT allow you to logthe Diagnostic Buffer entry into your DCS's alarm system) 2.) Use an SNMP OPC Server: I do unfortunately not know if this a.) allows you read out the CPU's diagnosticbuffer information and b.)if SNMP variable readingstill works when the CPU is in Stop soplease read up more about this at the link below and prepare for some R&D workshould you you decide to go down this path: SNMP OPC Server I hope the above gives you food for thought anyhow,good luck and let us know how it all turned out
	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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2/18/2010 9:59 AM	Rate (0)
AHWHG Posts: 3 Rating: (0)	Hello, Your idea is spot on I am going to use the web browser although I will have to upgrade my 317 to the latest one with the inbuild web browser. I did fine another way if you are interested and this is to use an addon siemens have that can be used on the S7-300 and can be used without Step7 or WinCC. £500 per PC though. http://support.automation.siemens.com/WW/view/en/9985721 Thanks for your help new 317 should arrive today and then I can get this project finished. Regards, Alastair.
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