Siemens S7 Modbus Switching over

Hi,

I am using Modbus protocol to exchange data between Siemens S7 and Foxboro DCS using CP341 (S7-300) redundant

communication looks healthy and the data transfer is fine, but the issue is Master Slave switch over happens every 1 minute, for that switch over time we are loosing the live data in the HMI of DCS....I don't know wat is wrong in this...

Suggestions please....let me know if you want anything specific....


Regards
Macs

Any Suggestions ?

What is redundant? CPUs or CPs?
Where did you get the redundancy sw?
Wouldn't it be wise to ask the code maker first?

kalle

Hi....Both the CPUs and CPs are redundant...
For making CPs redundant some codes have been written with 4 different DBs (2 DBs for Mod_Slave A and 2 DBs for Mod_Slave B) and it moves the data to each other by two function and it is executed by OB1.
The code maker has resigned the job and gone some where......this issue is here for past 7 months. no one is ready to take this....

Regards Macs....

Hmm, a one of a kind solution...

Is the Foxboro the Modbus master and the 2 x 2 CP-cards slaves?
With identical node number? The master does the switchover?

How is it intended to work? You don't have a flowchart / connection diagram / HW configuration to show us?


Kalle

Seen this?

https://www.automation.siemens.com/...11275147&Highlight=&Query=&cssearchengine=NEW

Maybe you can find something helpful in the chapter 'Creating the user program'.

Kalle

thank you...will have a look at it....in the meantime...i will try to send you the hardware configuration / flow chart...