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reading CPU status via OPC

Created by: tomearp at: 6/21/2009 6:58 PM (6 Replies)

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6/21/2009 6:58 PM	Rate (0)
tomearp Posts: 51 Rating: (3)	on an S7-300 CPU (6ES7315-2EH13-0AB0) is there a particular memory location that contains a bit (or byte etc)that holds the current operating mode of the CPU? if so, is the location writeable? (eg. to allow monitoring/control of the operating mode via an OPC server) many thanks
tomearp Posts: 51 Rating: (3)
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6/21/2009 7:14 PM	Rate (0)
umencho Diamond Expert Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	Hello, Look at How to get the system LED status So, you just need to connect OPC to CPU. (Ethernet, MPI or Profibus). Deppending what kind of hardware you have. Here also you could find more info about how to establish connection (more of examples use Simaticnet OPC server) regards Hristo Mihalev

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6/23/2009 2:46 PM	Rate (0)
tomearp Posts: 51 Rating: (3)	thanks for that, i'm not sure that will do what i want though. if i'm reading it right then you have to periodically call the SFC to extract the status info, which can then be transferred into a DB or some other memory location. but if the CPU has entered the STOP state then it won't becalling the SFC to update the status info and i won't be able to read it out over OPC anyway?
tomearp Posts: 51 Rating: (3)
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6/23/2009 4:13 PM	Rate (1)
J_Bell Posts: 5822 Rating: (412)	Dear Tomearp, well, why don't we try to use some fantasy in this situation? Let us think. The PLC CPU has suchnice features as the clock byte, doesn’t it? So this byte changes continuously as long as the CPU is in run. So if you constantly read this clock byte by your OPC and you notice once that two values of this clock byte are the same... the CPU must be in stop mode, don't you think? Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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This contribution was helpful to 1 thankful Users tomearp

6/23/2009 4:57 PM	Rate (0)
umencho Diamond Expert Joined: 3/21/2006 Last visit: 1/14/2025 Posts: 10239 Rating: (1182)	Hello J_Bell, Yes, your idea isn't fanastic. I can say perfect. Like watchdog trace. Best regards Hristo Mihalev

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This contribution was helpful to 1 thankful Users J_Bell

9/13/2009 4:52 PM	Rate (0)
tomearp Posts: 51 Rating: (3)	thanks for your input :) i set up a simple FB to toggle a DB bit everyfew secondsand got the Alarm package in the system's HMI to monitor the bits on the various controllers so if they didn't change for more than 15 seconds it would raise an alarm
tomearp Posts: 51 Rating: (3)
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9/13/2009 8:10 PM	Rate (0)
ddg Posts: 261 Rating: (42)	tomearp thanks for your input :) i set up a simple FB to toggle a DB bit everyfew secondsand got the Alarm package in the system's HMI to monitor the bits on the various controllers so if they didn't change for more than 15 seconds it would raise an alarm If you make the alarm bit in S7 , by monitoring the CPU clock byte may be it will not helpful to you if you’re CPU goes to stop mode. On other hand if your 15 sec. monitoring is done by your HMI then its okay. With best regards ddg
ddg Posts: 261 Rating: (42)	Last edited by: ddg at: 9/14/2009 4:51 AM
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