# API access to Latch in PID Controller & Laser Lock Box

**URL:** <https://forum.liquidinstruments.com/t/api-access-to-latch-in-pid-controller-laser-lock-box/1247>\
**Category:** Software & APIs\
**Created:** [November 9, 2025, 7:50pm UTC](https://forum.liquidinstruments.com/t/api-access-to-latch-in-pid-controller-laser-lock-box/1247 "2025-11-09T19:50:10Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![dgrass](https://avatars.discourse-cdn.com/v4/letter/d/839c29/32.png) [@dgrass](https://forum.liquidinstruments.com/u/dgrass)\
**Post date:** [November 9, 2025, 7:50pm UTC](https://forum.liquidinstruments.com/t/api-access-to-latch-in-pid-controller-laser-lock-box/1247/1 "2025-11-09T19:50:10Z")

</div>

I don’t see API access to the “latch” before and after the PID control filter in the PID controller (and the latches after the controllers in the Laser Lock Box). Does the ability to open and close these latch exist? If not, could it be added?

---

<div class="post-metadata">

**Author:** ![NandiW](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.liquidinstruments.com/nandiw/32/238_2.png) [@NandiW](https://forum.liquidinstruments.com/u/NandiW)\
**Post date:** [November 10, 2025, 3:52am UTC](https://forum.liquidinstruments.com/t/api-access-to-latch-in-pid-controller-laser-lock-box/1247/2 "2025-11-10T03:52:25Z")

</div>

Hi @dgrass,

Thank you for your question, you can control these switches with the following functions:

PID Controller:

- Switch before the controller is controlled through the [enable\_input()](https://apis.liquidinstruments.com/api/reference/pid/enable_input.html) function
- Switch after the controller is the `signal` parameter in [enable\_output()](https://apis.liquidinstruments.com/api/reference/pid/enable_output.html) function

Laser Lock Box:

- The switch after the controller is also the `signal` parameter in [set\_output()](https://apis.liquidinstruments.com/api/reference/llb/set_output.html) function

I can see the documentation is not as clear as it can be, we will add some more description to make sure this is explained more in detail.

---

<div class="post-metadata">

**Author:** ![dgrass](https://avatars.discourse-cdn.com/v4/letter/d/839c29/32.png) [@dgrass](https://forum.liquidinstruments.com/u/dgrass)\
**Post date:** [November 10, 2025, 8:22am UTC](https://forum.liquidinstruments.com/t/api-access-to-latch-in-pid-controller-laser-lock-box/1247/3 "2025-11-10T08:22:32Z")

</div>

Hi @NandiW, ah yes I missed this. Thank you!