you say, that it is possible to use ISO-on-TCP, i. e. RFC1006 with S7 fault-tolerant connection between CP1623 and S7-400H. You gave a link to manual S7-400H, but it is wrote there:

"Fault-tolerant communication is possible over Industrial Ethernet only with the ISO

protocol" (page 167). Is this manual obsolete?

My problem is about strange working of fault-tolerant system. I use (CP1623+redconnect+S7-400H) with ISO-on-TCP, and it works fine until I shutdown first S7-400 of pair of it. Then I see in "S7 redconnect diagnostic tool" that Path0 has status ABORT and Path1 has status DOWN after some time after shutdown. Then whole connection gets status DOWN and no data can be read from PLC.

In normal situation Path0 and Path1 have PROD and STANDBY statuses. And there is another strange thing - Path0 always has status PROD and Path1 always has status STANDBY, independent of blinking indicator MSTR on PLCc. Is it normal?

Please, help me to solve this issue.