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PG_IL

Need help with OB16E

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I am trying to determine or find any figures that could assist in obtaining the lifespan of a single output of a 1756-OB16E output card. I have a signal sending 400 pulses a minute to an output. I am starting think about when this card or output may need to be replaced before failure. I was given a MTBF range by Rockwell for the card itself but they could not expand on the likelyhood of the output failing exponentially due to the rapid signalling. I could also not find anything in the manual itself that could provide me with an idea of longevity, I could be missing it? Also with this project I experienced something odd with the originally scoped hardware, a solid state 24VDC relay (700-HLS1.) By measuring the resistance I was able to see that the relay should have been opening and closing but the signal was not being received. So, I swapped the solid state relay for a mechanical relay and it worked fine. I was curious if the leakage could have an effect on this. The problem with the mechanical relay is that the life is dramatically reduced to about a month for this installation, life for the relay is shown at about 10,000,000 actuations. I was hoping to have this working with a little longer life expectancy. If anyone has any experience / tips / or suggestions it would be much appreciated! PG

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Absolutely, leakage could have been the problem in the original installation. I've never tried to predict the failure of a solid-state circuit subjected to rapid cycling. Much depends on the load, and if yours was small enough that leakage didn't trigger it then maybe it won't heat up the OB16E's output circuit much and won't have large surge currents. What is the load device ?

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The device is an industrial printer. I am testing with two different printer companies and I am currently trying to obtain their internal wiring diagrams. I am sending two separate signals, incrementing their serializer and resetting the serializer count. These are the rapid signals that cause concern for hardware longevity.

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