Emergency Stop Circuit

I am planning to implement a hardware emergency stop circuit using a contactor on the mains that will be latched via the coil voltage accross an additional terminal on the contactor after the NO ready switch energizes the coil. Similar to a motor Start/Stop Circuit.

This circuit relies on the NC ESTOP switches to be wired in series of the latched coil voltage, so when depressed it opens the coil circuit and disconnects the mains.

My question is how do I tie in my control to this to have the the ability to TRIGGER an Estop via software? I will have an additional terminal that will tell the control when the contactor is in estop state.

Any ideas are appreciated.

Its not really well documented but you can create an estop chain in software using estop-latch. I have several things that can trigger an estop including the software button activated in this way. I think the docs just show a software and hardware estop button chained together. but the chain can be extended.

a simple or chaining can also do the trick and it very easy to read in hal
also to setup and view the nets in GUI as pyvcp led perhaps

What I'm trying to figgure out is on the hardware side. Once that estop signal is is generated in software, how can I use that signal to physically break the circuit powering the coil that is keeping the contactor latched supplying mains power? I need it to work in a way similar to depressing a NC ESTOP switch in that circuit and forcing the circuit open dropping power from the coil and unlatching it until the alarm is cleared and the ready button is pressed again.

Also would it be an issue to switch a 24v "coil" on an SSR using the 24v output on my 77i76e? I'm not sure what the draw is on the 24v "coil" side of the relay is.

Type_Zero_Design wrote: Also would it be an issue to switch a 24v "coil" on an SSR using the 24v output on my 77i76e? I'm not sure what the draw is on the 24v "coil" side of the relay is.

SSR use litle current to activate, so using 7i76 field outputs is safe, just check the alowed voltage for the SSR, almost all that i have are strictly 5V. That can be aranged with a single resistor, but some testing is in order if it does not have the current writen ( usually they do not ), or use a lab power supply to check how much it draws at 5V and calculate the resistor value based on that.