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| 3/24/2009 6:46 AM | |
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Dear Sir/Madam,I am using S7 400 with following hardware (See attached images in IMAGES.zip folder): 1) 6S7 414-2XK05-0AB0 / V5.12 Set 2) 6S7 153-2BA02-0XB02 Set 3) 6S7 341-1CH02-0AE04 Set (2 IN EACH IM153) Using redundant system for modbus communication. Modbus controller are of from Yokogawa (UT351,US1000 total 30 numbers.) Result obtained: 1) Redundancy is established properly. (Switching CPU A TO CPU B and vice versa is absolutely fine. Even Switching of redundancy from IM is OK.) 2) When I power up the system then communication of all 4 Cp 341 starts properly. 3) First time when I am switching the Redundancy then some time only 2 CP some times only 1 cp communicates with modbus device. 4) Again when I switch back to CPU A then all CP starts communicating. And now onwards for CPU switching communication works fine. 5) If I power off one master IM from second IM station (where 2 set of Cp 341 are placed) and again power on the IM then redundancy get switched properly but Communication for those particular 2 Cp 341 get stopped or only one CP communicates with modbus device. 6) Once communication started for all 4 CP 341 by 2 -3 times switching CPU then it works without any halt. So logic written for modbus is correct. Program care taken: 1) Modbus program is called in redundant area. 2) Redundant data is not configured (As it is not required). 3) When ever Any CPU becomes Master then it calls initialization FC where all communication related parameters like start addr, base addr, slave addr,length,modbus start addr are reconfigured. 4) Then logic waits for 5 sec to give first send request to first CP. For this 5 sec. “Master Reset bit” of send and receive FB of modbus block is kept high. After 5 sec Reset bit is made low and first send request is given to CP. Then this reset bit is always low up till next CPU switch over. 5) For next CP 341 logic waits for 10 sec 15 and 20 sec. and then sends first send request. 6) For slave CPU logic is not getting scanned as per redundancy standard. Please suggest me what change should be made in configuration or program to remove this communication problem. AttachmentIMAGES.zip (326 Downloads) |
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