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OPC Server detecting CPU state

Created by: EQUANS_MMA at: 5/8/2007 4:17 PM (3 Replies)

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5/8/2007 4:17 PM	Rate (0)
EQUANS_MMA Experienced Member Joined: 12/19/2006 Last visit: 11/21/2024 Posts: 12 Rating: (0)	Hello everybody I am using a OPC Siemens server with an S7 connection to a S7-400 CPU. Is it possible to detect with e.g. the quality code of a tag, if the CPU is in the STOP mode? Now, if the CPU enters the STOP mode, the connection between the OPC server and the CPU remains established. So the quality of the tag is good, but the data in the CPU can be wrong. Thanks

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5/8/2007 6:54 PM	Rate (0)
Calm_down Posts: 324 Rating: (30)	Hello Stohr, well, this is exactly the Problem with S7 Connections. They stay active even if the CPU is in Stop, but this is required to allow Step7 to access the PLC at this time too. To get rid of this Problem I would check the cyclic counter of the CPU all the time, if the value does not change the CPU is in Stop . Well welcome back the Live Bit... isn't it. Stay calm.
Calm_down Posts: 324 Rating: (30)
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5/10/2007 3:50 AM	Rate (2)
Dec Gold Expert Joined: 5/19/2006 Last visit: 12/3/2024 Posts: 549 Rating: (107)	Well,I can tell you thatWinCC and even S7-OPC Serverchecks theCPU-Status by reading szl-id 0x424. You can use (undocumented) OPC connection internal tag &szl(szl-id[,szl-index]) ex &szl(424) to read "processed operating mode transition (bzinfo)" see attached screen. The return value is variant of byte []. The 12th byte (0x8) isbzu-idas follow: 1-STOP(update); 2-STOP(memory reset); 3-STOP(self-initialization); 4-STOP(internal); 6-START-UP(complete restart); 7-RESTART; 8-RUN; A-HOLD; D-DEFECT; Dec Attachment cpu_status.zip (859 Downloads)
	Last edited by: Dec at: 10.05.2007 04:44 Last edited by: Dec at: 10.05.2007 04:34
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5/10/2007 8:50 AM	Rate (0)
Dec Gold Expert Joined: 5/19/2006 Last visit: 12/3/2024 Posts: 549 Rating: (107)	Same but using OPC Explorer with Synchronous I/O Group; In OPC-Scout you can't setup Synchronous I/O group so the quality is bad and no data. You have to use property window. Dec Attachment cpu_status_OPC_Explorer.zip (850 Downloads)

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