HelloLogic Editor

[Rich-C]

Hello All,

I am trying to write some logic but not succeeding at it. I have an on/off switch I turn on for a contactor and an Estop button to turn off in case of an emergency.

example:

step 1 - switch turns on the contactor 

step 2 - engaged the Estop (switches the contactor OFF)

step 3 - disengage the Estop contactor goes back ON

I want the system to reset after I disengaged the Estop and NOT go back to online until I reset the switch back to off and on again.

any advise??

[MikaelKrantz]

What type of system are you using?

[Rich-C]

 I am using a scadapack 474 with some relays. 

[Joel_Weder]

Hello,

I suggest you attach a copy of your application, or at least a screen capture of the logic section. Very hard to guess what might have gone wrong, as there are so many possibilities.

[BevanWeiss]

An EStop is a component of a safety system.  You should engage an adequately competent and certified professional to assess the required safety integrity of the system, and to validate that the as-designed and as-built system meets the functional safety requirements.

The logic that you are looking for is something of a rising edge trigger, and then a hold in, with a drop out.

Here's a slightly horrible example in Ladder Logic (where it didn't have an RTrig or similar.. so I had to create similar from scratch, as 'AND NOT PrevRunSwitch')

NOTE: This logic is not adequate to meet ANY required safety integrity requirement.  Additional consideration and assessment would be required to determine the adequacy of the logic above for any purpose.

The reset of the EStopOK circuitry would be handled by a separate safety related system, which would ensure adequate levels of integrity around the EStop, and device inhibit on EStop.  It would also perform the reset of the EStop (because the EStop should only be allowed to Reset if the safety related components have been confirmed as being 'healthy')