Redundant Modbus RTU on PM864 with two CI853

Hello All!
I have a task to make Modbus redundant communication with redundant PM866 and two CI853, each connected to own CPU. As far AC800M has no built-in redundant Modbus functionality, could redundant switchover of two CI853 be realized in customer code?
Thanks in advance.

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Rank: 20

Asked 4 years ago

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Hi,

I dont have much idea with respect to RTU.

I guess you make it work as dual or parallel communication with all the ports. We can not call it as redundant.

We were having similar case where Redundant 800M Controller with 2 Ci853 cards needs to communicate with ABB Safeguard system (2 Controllers having communication card with 2 ports each on card).Attached pic will tell you how we did communication.

Also we might have to do extra program on both sides to establish communcation for each ports.

Application Document attached fyi

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Poorna Chadra Rank: 82

Answered 4 years ago

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Thanks Poorna!

My case is almost yours one - one line (first port) from first CI853, connected to primary PM, is going to first port of partner and one line (first port) from second CI853, connected to standby PM, is going to second port of partner. May I ask you show me hardware configuration of your redundant CPU and port configuration of CI853?

Thanks in advance.

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by Poorna Chadra Rank: 82 on 6/25/2014 3:38:34 AM | Like (0) | Report

This programming i did some where during 2006, unfortunately i dont have any backup of screenshots to show how hardware configuration did.

by EK AKS expert

Rank: 20 on 6/25/2014 5:08:00 AM | Like (0) | Report

I suppose that, as far CI853 can not be marked as redundant in oppjsition CI854 for example, you installed two CI853 under the redundant CPU. Do you remember how did you handle loss of communication and switchover if status was not good over one of ID? Last page in your pdf is filled with black - maybe you have other version of pdf? Thanks!

by Poorna Chadra Rank: 82 on 6/25/2014 8:46:46 PM | Like (1) | Report

For each port we created separate MB Connect Block to connect slave port. All the communications are parallel. there is switch over kind of programming done. We did same thing in PLC(Safeguard system) also.

For eg we are reading particular tag from PLC, in 800M Side we will create only one variable and that variable will be linked to all MBRead register connecting to different ports in PLC side.

Some issues seen when there is a mismatch in the value sending from PLC Primary and secondary controllers, during those conditions in 800M side there will regular fluctation happening on the values shown on faceplates.

Other than this we have not done any special things. I really dont know it was right to do like this or not, but it was matching requirements of the customer.

And when ever there is failure in one port, still we will be getting values from other PLC side in other CI853 port which is still communicating.
Unfortunately the file which i attached previoulsy is bit corrupted,hence it is showing black.
I will try to get controller and application documentation form site, if any one from abb available now. If i get i will post you ack the documentation,

by EK AKS expert

Rank: 20 on 6/27/2014 8:23:33 AM | Like (0) | Report

Poorna
I'll be very thankful to you!

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Rank: 20

Answered 4 years ago

Hi Poorna

Did you find smth on the site?

Thanks

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Rank: 20

Answered 4 years ago

please find the attached controller documentation for your reference. Hopefully it will help you out in fixing your issue.

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Poorna Chadra Rank: 82

Answered 4 years ago

A20N4.doc

Hello Poorna

Thank you very much for document. I see that four CI853's are declared in HW structure, each with two channels. Is CPU redundant? May I ask you for screenshot of HW structure for clear understanding?

Thanks again!

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Rank: 20

Answered 4 years ago

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Redundant Modbus RTU on PM864 with two CI853

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