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Hello everyone; Long time no chat, been way too busy. Got to cruise the forums for some pay-back after this, it's been a while since I gave back. We've run into a problem beyond my experience, so I have a question for people well versed in the Modicon PLC remote I/O world. We're having some drop-outs with a remote rack of a quantum PLC system, and can find no problems with the cables, taps, or the RIO drop card. We're seeing what seems like a lot of retries, but then we don't know what constitutes a lot. There are 10 drops on this PLC. Drops 1, 9, and 10 are quantum and drops 2-8 are old 800 series. It's a CRP931-00 remote I/O head with a bunch of J890-001 cards, and two CRA-931-00 for the new racks. Funny, but the two quantum racks have the most retries of all the cards. A couple of the 800 series have almost no retries by comparison. The quantum drop 9 has had dropouts at random, sometimes twice or three times a day, sometimes none for a couple days. Causes major problems, obviously. Drop 9 is actually at the end of the trunk cable, so it's got the terminal resistor on one tap. Drop 10 was added later between drops 3 and 4, and has more retries than either of them, but no dropouts. We've asked Schneider for a contractor who can perform a RIO cable network integrity test, but it seems to mostly be these two quantum heads with the most retries, and only the one has been dropping out. Is there anyone who has seen something like this and can comment? We've changed almost everything around it and there's been no change to the retries, and the occasional drop-out still happens. Hope things are going great for everyone out there. Happy programming, speakerman.