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different type cpu928 and cpu928b running together possible or not?

Created by: hazem at: 6/22/2010 6:07 PM (2 Replies)

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6/22/2010 6:07 PM	Rate (0)
hazem Bronze Member Joined: 2/15/2010 Last visit: 1/20/2024 Posts: 329 Rating: (6)	Dear All, I have to line including the following two cpus 928(plc1) with coordinator and one cpu 928(plc2) and communicate via cp so one cpu. the cpus 928 with coordinator directly connected to hmi and the other cpu connected to cp and cp connected to each other .suppose there is any error it appear on the hmi. one day the reset switch broken and i changed one of cpus 928 with 928b i found the system is running perfect but always alarm came there is communication fault betweenplc1 and plc2 .i tested all fucntion found every thing is running perfect except that false message even also i tried to make fault for plc2 found every thing appear at HMI withou any prolbem only that false message came. my question is that cpu928 and cpu928b cann't work together or what ? or it can work together with this false message?
	Hazem
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6/23/2010 6:09 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 10/6/2024 Posts: 3024 Rating: (1054)	Hello hazem ifI understood you correctly, you have two PLC's all up. PLC"1" has a Coordinator card, two 928 CPU's and a CP (Ethernet CP143, Profibus CP5431 ..?) forthe comms link to PLC"2". PLC"2" hasone 928 CPU's and a CPfor the comms link to PLC"1". You replaced one of the 928 CPU's with a 928B CPU and now have an Alarm on the HMI that states that there is a communication failure between the two PLC's, but the system is behaving/controlling ok in all other respects. I hopeI got it right so far and as for your question "my question is that cpu928 and cpu928b can't work together or what?"my answer is: It didn't matter which of the three 928 CPU's was replaced by a 928B, they can all work together. You can "mix and match" different CPU's within an S5 (Multiprocesor mode) and of course communicate between different PLC's with different CPU's. I suggest you check your logic for what condition is responsible for the communication Alarm. It could for example be that the comms watch dog timer logic has been based on cycle time rather than a fixed time. Since a 928B is quite a bit faster than a 928 CPUthiscouldexplain that it now causes the Alarm. I hope this helps
	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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6/24/2010 10:43 PM	Rate (0)
hazem Bronze Member Joined: 2/15/2010 Last visit: 1/20/2024 Posts: 329 Rating: (6)	Dear Fritz, I will try to do so when the chance came ?
	Hazem
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