Simple E-stop string
Simple E-stop string
(OP)
Does anyone know of a circuit or device that would let me have a simple series e-stop string (using one N.C. contact per e-stop only) and still get individual status of each switch?
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RE: Simple E-stop string
You could pull a connection off of either side each of your e-stops and run that through an LED back to your supply to indicate switch status.
Regards,
Rich...
Richard Nornhold, PE
http://www.ovenind.com
RE: Simple E-stop string
Keith Cress
kcress - http://www.flaminsystems.com
RE: Simple E-stop string
Regards,
Rich......
Richard Nornhold, PE
http://www.ovenind.com
RE: Simple E-stop string
Roy
RE: Simple E-stop string
Keith Cress
kcress - http://www.flaminsystems.com
RE: Simple E-stop string
Yes I guess that might work, assuming you had an E-stop relay.
When you push an e-stop the relays N/O contact disconnects the coil from the circuit and its N/C contact then connects an Ohmmeter to measure the loop resistance. You would just have to be careful that the resistors were high enough in value so as not to hold the e-stop coil in.
Of course you would need a pushbutton or something to reset the E-stop relay
I think it would be easier to do with a low Voltage DC rather than AC.
I wonder if there is something in the code that would preclude you from doing it?
Regards
Roy
RE: Simple E-stop string
Use a ratiometric voltage reference for your DAC and the trip point for the comparator. Maybe add a small decoupling capacitor to smooth out the inputs a little.