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Old March 8th, 2018, 11:35 AM   #12
Mispeld
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Join Date: Feb 2017
Location: VA
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With a U3K Sercos drive, you will need to have that Drive Enable input energized, unless there is some way to get around it by going directly into the drive to bypass it. Since it had been a working system, this is probably not what you want to do.

Rather, you want to get I/O power on pin CN1-31, the dedicated Enable Input for U3K Sercos drives. In one of the pictures, it looks like a "home-made" cable on CN1. So you will need to figure out which wire corresponds to pin 31, and check whether it has somewhere between 12 and 24 VDC on it. Maybe there are drawings to help, or wire labels, or clues from the other two drives. If you can measure volts on the wire, then the D-shell connector would be something to examine (also important would be CN1-27 IO common).

On the other hand, if no voltage on the wire you think is going to pin 31 (referenced to the wire you think is going to CN1-27), then you need to go back in the circuit to see what supposed to be enabling the drive, such as an auxilary contact from the main power contactor. Since you have bus power, the controlling contactor appears to be pulled in. This implies E-stop circuits are OK. Maybe another process stop is active.

As a side note, the Allen-Bradley part 2090-U3BB-DM12 is a convenient way to access CN1 for limited, but typical, control of the Sercos drive. This may be a better option than re-building a faulty cable or connector going into CN1. I would guess this product was not available when your system was built.
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