ETN21 & 4 PLC

[valerio81 0]

Hi to everyone. i have a problem. i have 4 plc that must communicate through 4 ETN21. i have set the 4 ETN with 4 address 192.168.0.xxx i want to use omron FB to do the communication.. i've tried to use the SEND block in one plc but the exit bit (ON) doesent work... someone can send me a little example and some help about??? thanks a lot.. valerio

[Nibroc 4]

... Example using Omron receive FB attached. Three PLC's in example. PLC0 - 192.168.0.9 PLC1 - 192.168.0.10 PLC2 - 192.168.0.11 PLC0 reads 10 DM words from each of PLC1 and PLC2 continuously, as fast as it can. All PLC's must have ETN unit mapped to network 1 using routing table setup. Nibroc ETN_Example.cxp

[valerio81 0]

hi. thanks a lot.. now the communication works very good.. another question about.. if i turn off 1 of 4 plc all the DMs keep the value and dont go to 0.. how can i reset the plc exchange memory if one plc turn off or stop communication? there is some flags?? (i.e. A219.00 etc...) thank again for your answer..

[Nibroc 4]

... You need to monitor the 'NG' output bits from each FB. If an NG bit is triggered (true only for one scan), there was a comunication problem to that PLC. Write some code to perform 'fault handling' to suit your application. Normally I would use a counter to count several NG returns to generate a fault. You could reset the counter with the respective 'OK' bit. Nibroc Edited 19 Sep 2006 by Nibroc

[valerio81 0]

thanks a lot again.. all right now... valerio

[BobLfoot 302]

Not sure how OMRON implements its messaging, but have found with Allen Bradley PLCs that it is usually faster to have all PLC's reading rather than a mixture of reads and writes. Hope what I am saying makes some sense.

[Harald_Brueck 0]

Thats not with OMRON PLCs. It is easier, I think, to do all communication only in one PLC. If you want to make it faster, you have to use only SENDs with no respond required. (especially if you have much more PLCs) Harald

[Nibroc 4]

... Hi Harald - (Welcome to the Forum, - I think I have seen your name on the Omron internal Discussion Board ?) Not sure if I would make one PLC the master, as then the entire system would rely on the master being available. I prefer to make each PLC 'RECV' the data it requires from its peers. I also prefer to use SEND / RECV with controller link, as this method is not as restrictive as the 'data link tables'. (Data link tables are probably much faster though) Nibroc

[Harald_Brueck 0]

RECV is even more reliable? - I agree. Harald