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Basic Functional Scheme for E-stop with Reset and EDM

Basic Functional Scheme for E-stop with Reset and EDM

Long-established Member

I have written a basic functional Scheme for an Emergency Stop with (Manual) Reset and EDM in ctrlX Safety Engineering. I would like some confirmation that this is the correct/best way to write this functionality. Or is there a better way?

The scheme outputs a signal Estop_Status that would drive an external relay with a N/C forced guided contact connected to an EDM input. 

Function Description:

  • Estop_Status off after power on.
  • Estop_Status off when emergency stop is pressed. 
  • Estop_Status off when EDM mismatch is detected.
  • Estop_Status Does not come on when EDM mismatch is cleared
  • Rising/Falling sequence on Reset input requried to turn Estop_Status back on
  • Reset input clears any previous EDM error

Functional Scheme below. 

Note: I have used a ctrlX PLC and functional I/O to simulate the external relay and adjust the EDM time to simulate faults. 




Established Member

Hi @bclapperton,

First I would like to tell you some limitations if you are using the current release SAFEX-C.1x Firmware and ctrlX SAFETY Engineering

  • EDM block reset is not working, the only way to reset the EDM block is to set the Start/Reset element as "Use as Alarm Reset", but this will reset all your PLC logic (Bug #584752)
  • For the restart of the Restart block you can use a normal Confirm Button, you don't need to use a Start/Reset element (you can use it if you want of course)

Because of these limitations I would not recommend to use the logic you posted on the current release sorry 😅


Regarding the application itself, I have 2 things to say:

  • Instead of using the Restart block to control the emergency button you can do this, it has the same effect:




  • Regarding the EDM, the function is to monitor loop feedback for contact multiplication following the cat 4 of EN 954 1, is this your use case?



Best Regards,


Long-established Member

Hello @BRamos,

Thanks for the information on resetting estop using Start Type: Monitored

Yes I am using the EDM for monitoring according to cat 4 of EN 954 1. This is a very common use case. I am happy to reset all the PLC logic for now. After Estop or EDM error the system should go back to start conditions anyway. 

Is there any plan to have an error reset block with a logical input? At the moment it looks like the only way error reset is the Start/Reset block which must be a physical input. Sometimes there needs to be multiple fault reset buttons or fault reset via higher level control via fieldbus. 

Established Member

Hi @bclapperton,

Happy I could help.

Regarding the EDM improvments, if you see the block properties:


You will be able to separate certain blocks into different reset groups, that you can safely reset without having to restart the logic.

For this reset you will be able to use the Start/Reset Input Element as "Use as Block-Reset", but this is not implemented yet.

Regarding the reset fieldbus, there is the function block "Reset from Network":


However, this block still has very limited operation on the current release:

  • It can only be used when SAFEX-C.1x is FSoE Slave or PROFISAFE Slave.
  • Only works as "Use as Alarm Reset" (Resets all logic).
  • Only works if it is connected to bit 0 of the F-Bus Input block.


Given our current timetable my recommendation is to build your project witout expecting these fixes soon.

Best Regards,


Community Moderator
Community Moderator

Hello @bclapperton ,

for EDM and Reset issues please follow the following Bug-IDs in our Extended Release Notes, that you will receive with every release: 501983, 584752, 642842 and 670720.

Since the question is answered for the moment, I close this with the relevant answers as "solution".

@BRamos : FYI

Best regards

Your ctrlX SAFETY team