# Latency on Switching Outputs

**URL:** <https://community.ecumaster.com/t/latency-on-switching-outputs/6329>\
**Category:** PMU\
**Tags:** document\
**Created:** [August 14, 2026, 5:07am UTC](https://community.ecumaster.com/t/latency-on-switching-outputs/6329 "2026-08-14T05:07:32Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![AaronPD](https://avatars.discourse-cdn.com/v4/letter/a/b5ac83/32.png) [@AaronPD](https://community.ecumaster.com/u/AaronPD)\
**Post date:** [August 14, 2026, 5:07am UTC](https://community.ecumaster.com/t/latency-on-switching-outputs/6329/1 "2026-08-14T05:07:32Z")

</div>

Hello,

I’m using a PMU24 and have a safety application that requires very fast switching.

If driven by a digital input pin, what would the latency (in ms) be for one of the outputs to change in reaction?

Any ways this could be optimised?

Thanks,

---

<div class="post-metadata">

**Author:** ![essess](https://avatars.discourse-cdn.com/v4/letter/e/d9b06d/32.png) [@essess](https://community.ecumaster.com/u/essess)\
**Post date:** [August 14, 2026, 1:40pm UTC](https://community.ecumaster.com/t/latency-on-switching-outputs/6329/2 "2026-08-14T13:40:29Z")

</div>

If safety related, I wouldn’t pass it through an ECU which can hang/reboot and power to ecu is controlled by a whole chain of other mechanisms.

How fast do you need?

---

<div class="post-metadata">

**Author:** ![AaronPD](https://avatars.discourse-cdn.com/v4/letter/a/b5ac83/32.png) [@AaronPD](https://community.ecumaster.com/u/AaronPD)\
**Post date:** [August 25, 2026, 4:37am UTC](https://community.ecumaster.com/t/latency-on-switching-outputs/6329/3 "2026-08-25T04:37:39Z")

</div>

Requirement is for a reaction time of \<10ms

---

<div class="post-metadata">

**Author:** ![noon.engineering](https://dub1.discourse-cdn.com/flex013/user_avatar/community.ecumaster.com/noon.engineering/32/7208_2.png) [@noon.engineering](https://community.ecumaster.com/u/noon.engineering)\
**Post date:** [August 25, 2026, 10:39am UTC](https://community.ecumaster.com/t/latency-on-switching-outputs/6329/4 "2026-08-25T10:39:04Z")

</div>

I believe the main loop runs at 500Hz, and will read the input and switch the output within one cycle provided the input is above the output in the project tree. MOSFET switching time should be in the ballpark of 0.1ms. Theoretically you should see \<3ms, but you’re obviously best off measuring it with real hardware and firmware.

Be aware that heavy CPU load could slow the main loop, timings will change with firmware updates, and that hardware and software errors _do_ occur. Depending on what you mean by “safety”, it may or may not be suitable (engine safety yes, human safety probably no).

---

<div class="post-metadata">

**Author:** ![Jadzwin\_ECUMASTER](https://dub1.discourse-cdn.com/flex013/user_avatar/community.ecumaster.com/jadzwin_ecumaster/32/28_2.png) [@Jadzwin\_ECUMASTER](https://community.ecumaster.com/u/Jadzwin_ECUMASTER)\
**Post date:** [August 30, 2026, 9:48pm UTC](https://community.ecumaster.com/t/latency-on-switching-outputs/6329/5 "2026-08-30T21:48:45Z")

</div>

The worst case scenario should be 4ms if you use digital input.