Run status

I know a motor run status is a discrete input into a PLC but how does a motor or VFD create that input?

From the most common type of VFD's and motors

Thanks

Open collector NPN (sinking) or contact closure (relay).

Most VFDs have a relay output for run status with a SPDT (Single Pole Double Throw) contact, one normally open close on run, and one normally closed open on run. Most motor starters have an auxiliary contact on the starter coil that changes state (from open to cloed or vice versa) when the starter pulls in.

There are lots of variations on these, so I always try to get specific info on the device I'm monitoring.

To clarify, a motor is not normally used to create a PLC input, but the motor control devices (motor starter or contactor, and circuit breaker) is used to control auxiliary dry contacts that do provide inputs to a PLC. There are some possible motor direct inputs, such as centrifugal speed switches and temperature switches, but those would generally not be used for typical motor control logic.

To echo Toms reply but add a point, as far as I have seen evey VFD I ever worked on has a set of nc,common, no contacts to get run status. What I have found is they are NEVER clearly lableds as such. Not wanting to be "that" guy, looking into the user manual for your specific drive will shed light on this. TL;DR Yes they do have a status contact, good luck finding it....

Noob, probably the reason the relay is not clearly labeled as to function is that the function is changeable in the drive parameters. In some of the drives I am familiar with, that relay can be set up to do about 30 different things.