S7-300 Software Redundancy DB Transfer to RESERVE PLC

Join Date
Jun 2005
Posts
54
Hi All,

I am using S7-300 CPU-317-2DP with IM 153-2 for Software Redundancy. I am using Ethernet as Redundant Link.

When the Master PLC is active, in FC100 we transfer redundant DB_NO = required DB NO and DB_NO_LEN = Required Length. This will transfer Data to Reserve PLC.

My question is how much length I can Specify to transfer the DBs?

Also when Master to Reserve Changeover takes place (PLC A --> PLC B Transfer),then PLC B now master takes few Seconds to takeover till then SF LED glows.
Is there any way to reduce this changeover time?

Thanks in advance for all your suggestions.

Best Regards,
PH
 
Both systems needs to be error free before trying to switch over. In case the led SF on the reserve station is ON before or during the change over something is wrong in our configuration. You must copy the hardware from station A to B (IM nodes). Do not change in both hardware configurations.
The transfer of data the opposite way, Reserve to Master, is possible but slow. At take a few seconds to transfer it.
The datablocks configured as redundant must be at least 10 bytes. The maximum length I don not know rigth now, but check the manual. But try to make only the "control logics" redundant. Calculations and other operations may be done in both processors but not redundant. Much datablocks set as redundant takes a lot of time to transfer it. Also because you must use redundant sfb timers in the program.

Note: Manual switch OVER from A->B as mentioned in the manual works fine. Manual switch OFF the redundacy as mentioned in the manual does NOT work. During switching OFF the redundancy all the outputs are OFF for a few scans. If you do it the "hard" way, switch A to stop. Everything works fine.

Regards
 

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