HPG800 Modbus TCP redundancy fail, In same IP address, Hot standby.

1.Please refer attached network schematic.

2.At both yokogawa Client module(A/B).

We set Server information to get modbus data.

and set same ip address(MAIN server/Back-Up server) at both yokogawa module.

3.Client B is not working until network A(Main server) would be dead.

Only Client B start working when network A is down(Back-up server start working instead of Main Server by same IP address of Main Server)

4.As per my knowledge, HPG shall works as dual in normal operation. means Back-up server also shall works always.

5.If I have to change IP configuration, Please let me know where and how I can change

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SEONDEOK Rank: 4831

Asked 4 years ago

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Hi. As you ahve setup two independant system with the same IP address, in most cases only one of them would give you data, given that there is a common source. In your diagrm you should two Clients A & B. It is not clear what these are. The HPG800 is designed as a Modubus Server or client, but for data gathering between system, not HMI's or other applications (in general). HPG800 can be redundant, but normally only respond a single controller (same IP) where the primary and secondary (reduna=dant controller are on the SAME network. That is (from your drawing) the Main and the Backup need to be on the same network with the same addresses, but only one of them is only at any given moment.

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by SEONDEOK Rank: 4831 on 8/4/2015 11:49:47 PM | Like (0) | Report

Dear Ingo

I really thanks to your reply.
First of all, HPG800 is designed as server.

Could you confirm my understanding?

1.Backup server may not send data in normal operation.

2.If two independent network connected each other, Client B can gathering data from Main server

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But I want gathering data from back-up server in normal operation.
As I know, usually (0.0.0.+1 or 0.0.+2.0) IP address sequence applied to back-up server.

So I set up that above IP address for Back-up server at Client B to gathering data from back-up server.
But I failed.

I want totally two independent network as redundant.

Is there any other way?

by Ingo AKS expert

Rank: 34 on 8/5/2015 5:11:29 PM | Like (0) | Report

Please understand the difference between Redundant systems (HPG800) and dual path (you're suggestions). The two are not interchangeable and will, in most cases not work. You can get third party "redundancy brokers" but I'm not sure if you can for Modbus comms. So answer your questions: 1. The backup HPG800, acting as a server, will not be able to communicate, as it is the backup node and therefore will not respond to calls, given it has the same IP, addresses etc. 2. If you setup a fully redundant commms, which is not possible for Modbus (see the Modbus standard), and the Client is also redundant (not usually) yes it could work...I would suggest you are trying to do something with a protocol which is not designed to purpose and you should try this in another way with other protocols. The HPG800 is fully redundant with two controllers, two network connections. Your "clients" do not seem to have this capability. Change this and you are set.

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Ingo

Rank: 34

Answered 4 years ago

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HPG800 Modbus TCP redundancy fail, In same IP address, Hot standby.

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