Winding project

So here I am at work, we just got this winding machine working that hasn't for a while (it had some stuff plugged in wrong inside). Now a winding machine is kinda a simplified lathe, without all teh fancy speed controls, not a very powerful motor either. Used for making electromagentic coils for magnets or transformers. On it theres a counter (says number of rotations since started, and when it reaches a set point shuts off the motor).

Now heres the plan, I want to try and make it so that when the rig finishes winding, it'll send a signal to an arduino so that it can for example, automatically log the amount of wire that's been used up being among the first parts. All the arduino programming is fine, what I'm wondering about is the circuitry.

From testing, the signal the counter sends to the motor controller to stop is is a 50-120V AC signal ( There is a foot pedal to tell the motor to run or not, when its pressed the signal is 120V, and when released the signal is 50V AC). I was thinking the easiest way to get a read off of this signal would be to have a branch of it drive a relay, and the power going through the relay itself would be the 5V or 0V for the arduino to know when its stopped. Theres also a 15V rotary encoder (one of the quad ones, works both directions) on the machine that I'd like to get a read off of as well, which I was thinking another 2 relays would probably do the trick.

So would relays be a good path to go, or would there be a better way to get a read off of the 2 signals. If the 120V AC were really that much of a problem to deal with, that could always be controlled by the 24VDC going out to the motor itself if that'd be easier to work with since itd go off when the signal to stop the motor goes.

The spindle control would be an appropriate place for a relay or 2.

Unless the encoder is reading really slow, relays wold not be much use for monitoring the existing encoder. You might be able to read it using voltage dividers, but you might want to run those signals through a stage or 2 of a 7414 to clean them up.

From what you say it sounds like the foot pedal sends 120V to the motor control, but when the switch is open the motor control is getting 50V? Sounds like some sort of solid state switch that is not turning all the way off. Might want to check and see if the foot switch is controlling some other device and that device is sending the power to the motor control.

The 24V to the motor might have a problem if the motor driver has asoft start and stop. The voltage might come up slowly so a relay migth miss a few turns of the spindle because the voltage wasn't high enough to turn on the relay.