glenncooper
Member
Hello. I've been working through a problem at one of my customer sites where a section of 1734 I/O is getting destroyed. Excuse the long explanation, but the situation takes a bit of description. We have five production lines that are built heavily on the 1734 I/O via DeviceNet. The lines are about 10 years old, and in general we get great performance from the Point I/O along with the expected occasional module failure. In the last month we've had two lines create multiple failures in exactly the same way on their respective identical I/O racks. Each rack contains 20 I/O cards - mostly a mix of IB4, OB4, ITI, OE2V, IE2V, etc. Because of the I/O count we have a 1734-EP24DC. And 6 modules from the that we have a 1734-FPD that allows me to have some 5 volt stuff. All of the modules that fail are failing between these two power distributors. We get one random module that fails and is destroyed (Module Status goes red). Then at some point we'll get another module that fails, and these keeps going. In every case the modules are electrically destroyed. I spent several days carefully analyzing the first line, looking for thermal issues, contamination, errant electrical surges, etc. I inspected the failed modules under a microscope to see if there was any sign of obvious electrical damage - none. I discovered an issue with one of the wiring bases not reliably sending one of the network signals down the bus. At the end of the day I replaced the EP24DC, the FPD, all of the terminal bases, and all of the I/O modules. That line has been okay for a month now. We've started seeing this identical sequence of failure on another line. I would really like to understand how a sequence of destructive failure like this can occur. If anyone has ideas or similar experiences I'd love to hear about them - Thanks much!!