Physical safety relay and software estop latch working together?

Hi,

I've been spending the last couple of days trying to figure out how to make the "software estop" work together with my safety relay. But i'm going in circles and i need a kick from someone, maybe you?

First off, i have this physical circuit to handle the emergency stop logic in hardware:
 
...the idea is that estop should work without any software involvement. And everything should be as redundant as could be. I have dual (safety) contactors(KM1 + KM2) that cuts power to all drives and at the same time prevents resetting the estop-circuit in cause of failure. I have a proper estop-button(it's redundant contacts, but only shown as one here in S5). On top of that i have added an inline relay, K13, which can be triggered by software, aswell as the wire "1" which goes to an input in LinuxCNC in order to tell it the state of the safety relay. There is a short delay(~0,5sec) between the two sets of relays in the safety relay, so ideally the signal to LinuxCNC should be able to tell the servos to emergency stop just before the power is killed. 

So far, so good. Everything works just like i want it. The latching works excellent and the signals to and from LinuxCNC also works as expected....

However, i'm totally going in circles when i try to add an estop latch inside LinuxCNC to work in conjunction with the hardware safety relay. I took inspiration from a thread from the user Unlogic  who seem to have it working. But i end up having a latch #1 that depends on latch #2 that depends on latch #1 again....ehh... so currently i'm just having the inputs tied into LinuxCNC like this:
..this "sorta works" and prevents anything powering on before LinuxCNC has booted properly. However the UI experience is kinda bad as i have to press a button extra and there is not really any feedback to the user

SO, the question: Has anyone got a combination of a physical safetyrelay and an estop latch to work "like it should"? I'd be very interested in seeing how others have solved this issue...

/Thomas

iocontrol.0.user-request-enable can be used as an estop reset signal (eg in place of S6). A short pulse is sent on this output for this purpose. I chose to just stick with the external reset button and connect to iocontrol.0.emc-enable-in, I used a relay on your S6 circuit to do this

If you want an internal estop and an external estop, multiple instances of estop-latch component should let you do this.

The hardwired diagram shows two normally open contacts in series  KM1 AND KM2 indicating that the Estop is active. The rest of the circuit is similar to what you had in mind. Please do not add a screen (UI) estop or reset buttons; make it a habit to only use the external hardwired estop and reset push buttons otherwise you defeat the use of a safety system. The hal block diagram I use it to generate the hal file but it might help you understand what the hal net file does.

 

#

---

# Load realtime Components and their counts

loadrt and2         count= 1
loadrt edge         count= 1
loadrt or2            count= 1

#

---

# Add functions to threads

addf and2.0         servo-thread 
addf or2.0            servo-thread 
addf edge.0         servo-thread 

#

---

# Set parameters

setp edge.0.in-edge          0
setp edge.0.out-width-ns   20000   

#

---

# Connect Pins with Wires

net external-ereset        and2.0.in0  
net external-estop         or2.0.in0  
net n.1                           or2.0.out  edge.0.in  
net n.2                           edge.0.out  halui.estop.activate  
net n.5                           halui.estop.reset  and2.0.out  
net soft-estop-active      halui.estop.is-activated  and2.0.in1  
net software-estop         or2.0.in1   

Benb wrote:

The hardwired diagram shows two normally open contacts in series  KM1 AND KM2 indicating that the Estop is active. The rest of the circuit is similar to what you had in mind. Please do not add a screen (UI) estop or reset buttons; make it a habit to only use the external hardwired estop and reset push buttons otherwise you defeat the use of a safety system. The hal block diagram I use it to generate the hal file but it might help you understand what the hal net file does.

 

  

I like your diagrams, what do you use to make them?

I'm not 100% sure the above diagram will work exactly like this with my setup, however your input sparked an idea to solve my "circular dependency" problem between the software and hardware latches: I need to use a "oneshot"-component to connect the two latches instead of connecting them directly(and thereby creating the problematic circular dependency). Sounds obvious now, not sure why i didn't see that option the other day. So thanks for the input, i think i have a viable way to solve this now!

rodw post=317388 userid=20660
iocontrol.0.user-request-enable can be used as an estop reset signal (eg in place of S6). A short pulse is sent on this output for this purpose. I chose to just stick with the external reset button and connect to iocontrol.0.emc-enable-in, I used a relay on your S6 circuit to do this

Thanks! I couldn't wrap my head around this at first, but i think i got the gist of it now. I'll try to implement this short pulse and post the solution here for future reference.

​​​​​​​Thanks!