UR5 safety wiring issue: Dedicated E-stop inputs fail, configurable safety inputs work

Technical Questions
1

Hello,

I am working with a UR5 robot and I have a question regarding safety wiring and dedicated safety inputs.

I have a safety setup where a safety relay controls auxiliary relays, and these auxiliary relays then control interposing relays before going to the robot:

Safety relay → Auxiliary relays → Interposing relays → UR5

I use the interposing relays because I want to keep the robot wiring separated from other components in the electrical cabinet. This was also a requirement in the project to avoid mixing internal robot signals with other system signals.

When I connect the safety signals to the dedicated Emergency Stop inputs (EI0 and EI1), I get the fault:

“Ports did not disconnect simultaneously”

However, when I connect the exact same signals to Configurable Safety Inputs configured for safety, everything works without any issue.

Some details:

  • Two-channel safety wiring is used

  • EI0 and EI1 are wired separately

  • SI0 and SI1 remain bridged if unused

  • The issue only occurs on the dedicated E-stop inputs

  • The configurable safety inputs work correctly

  • I am currently using standard auxiliary/interposing relays because all safety relay outputs are already occupied

My questions are:

  1. Can the dedicated EI0/EI1 inputs be more sensitive to timing differences between channels than configurable safety inputs?

  2. Could the auxiliary/interposing relays introduce enough delay to trigger “Ports did not disconnect simultaneously”?

  3. Is it acceptable to use Configurable Safety Inputs as the main robot safety interface from a safety relay?

  4. Would using configurable safety inputs affect the robot’s safety level (PLd / Cat3)?

  5. Has anyone experienced a similar issue with UR5 safety wiring?

Any advice would be appreciated.

Thank you.

2

hi, try to see this article.

Universal Robots - Connecting an Emergency Stop Device vs. a Safeguard Protective Device

3

Thanks.

But can I use the configurable input as the main external emergency connection? Without loosing the safety rating.

I can’t use the dedicated emergency input because the fault I’m getting.

4

you can configure the configurable input as you need, also for emergency stop

image
image1002×882 140 KB

5

Does it give it the same PL and Cat safety rating?

6

well… I suppose yes, because there is no reason that will be different. for sure you can ask to UR support.

7

  1. Can the dedicated EI0/EI1 inputs be more sensitive to timing differences between channels than configurable safety inputs?

    1. I doubt it. Sounds like a hardware fault to me. Are you able to test with a button and double contacts? Or a single relay?

  2. Could the auxiliary/interposing relays introduce enough delay to trigger “Ports did not disconnect simultaneously”?

    1. Doubt it. A physical emergency button with two contacts should introduce more delay opposed to each other in my opinion.

  3. Is it acceptable to use Configurable Safety Inputs as the main robot safety interface from a safety relay?

    1. Yes.

  4. Would using configurable safety inputs affect the robot’s safety level (PLd / Cat3)?

    1. No.

  5. Has anyone experienced a similar issue with UR5 safety wiring?

    1. I haven’t and I have installed many robots now. However worth mentioning, I rarely use the EI terminals and almost always the Configurable Inputs.

:slight_smile:

8

Thanks for answering my questions.