# SLB Flood Port Trigger with ATC **URL:** \ **Category:** ❓ Question\ **Created:** [November 3, 2026, 10:55pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581 "2026-11-03T22:55:03Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![misquamacus](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/4af34b/32.png) [@misquamacus](https://forum.sienci.com/u/misquamacus)\ **Post date:** [November 3, 2026, 10:55pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/1 "2026-11-03T22:55:03Z")
I have a newly assembled Altmill 4x4 w/ATC and it is working great, but I can’t get it to turn on my dust collector. I have the Flood port wired up to the recommended IOT outlet, but I’m not sure how to actually make it trigger. On my other machine (different brand) I just press the “Coolant” button and the dust collector turns on. Pressing the Flood button in the Coolant menu on this Altmill just drops the tool out of the ATC. Any help would be appreciated. ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [November 4, 2026, 12:46am UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/2 "2026-11-04T00:46:02Z")
@misquamacus Welcome to the group. I don’t know anything about how the ATC is connected or run by your controller. However, in the tech manual, this is what it says about running things connected to the Flood port: "Flood If you’ve used a ‘Coolant’ output previously, this 5V output still serves the same function. Simply turn the digital signal on or off using M8 and M9 commands either manually, in g-code using your post processor, or using your g-code sender’s start/end g-code code blocks. This output is commonly used to automatically control a vacuum or router to turn on/off at the start/end of a job using an IOT Relay. It also can be used for any other purpose with any component that accepts a 5V 40mA digital signal." ---
**Author:** ![KGN](https://forum.sienci.com/letter_avatar_proxy/v4/letter/k/c77e96/32.png) [@KGN](https://forum.sienci.com/u/KGN)\ **Post date:** [November 4, 2026, 1:27pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/3 "2026-11-04T13:27:11Z")
You likely have the event out trigger set to an ATC port. Once connected, go to Config → Accessory outputs. You can see the 4 triggers configured ($750 → $753) and the 4 ports ($760-\>763). These trigger on the firmware side for specific actions, like spindle on, coolant on, etc. ![image](https://forum.sienci.com/uploads/default/original/2X/0/0974c73d37b2eda158002353345a8285493ebc3f.png) If you have an ATC and have gone through the setup - 3 get set by us (1-3) in P999.macro as part of the ATC configuration wizard if you’ve gone through that. > 4 is left alone, and default has it set to M8 (your flood) triggering port 3 - you probably want to disable this and restart your controller after resetting. Set the trigger to none like the ATC macro does for 2 of the other 3. ![image](https://forum.sienci.com/uploads/default/original/2X/d/dd4e878ebfa851d411a2e03d1c06e41afc9a7baa.png) ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [November 4, 2026, 1:36pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/4 "2026-11-04T13:36:28Z")
@KGN That’s what I was trying to say. 😀 😀 ---
**Author:** ![KGN](https://forum.sienci.com/letter_avatar_proxy/v4/letter/k/c77e96/32.png) [@KGN](https://forum.sienci.com/u/KGN)\ **Post date:** [November 4, 2026, 1:42pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/5 "2026-11-04T13:42:09Z")
Alas “Event port drops my tool out” has come up before with a third party system. > [@Gsender turning on Switch when spindle activates](https://forum.sienci.com/t/gsender-turning-on-switch-when-spindle-activates/25461/2): > > So you didn’t include any relevant information about your hardware setup here but I’m going to use the assumption that you are using some sort of grblHAL device. It’s possible that you have an event linked in your firmware configuration to a specific AUX pin for the spindle on trigger (M3/M4) If you’re using SienciHAL (SLB or SLB-EXT without having flashed a more recent version of grblHAL): You need to check that whatever port your ATC switch release is set to does not trigger on M3/M4. This… ---
**Author:** ![misquamacus](https://forum.sienci.com/letter_avatar_proxy/v4/letter/m/4af34b/32.png) [@misquamacus](https://forum.sienci.com/u/misquamacus)\ **Post date:** [November 4, 2026, 3:17pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/6 "2026-11-04T15:17:25Z")
That solved it! Thanks for your help. My experience with the machine, and this software has been great so far. Your documentation and videos are impeccable. That dust collection trigger issue was my only bit of confusion, so it might be worth putting a specific mention somewhere in the ATC documentation. Thanks again! ---
**Author:** ![gwilki](https://forum.sienci.com/user_avatar/forum.sienci.com/gwilki/32/366_2.png) [@gwilki](https://forum.sienci.com/u/gwilki)\ **Post date:** [November 4, 2026, 4:28pm UTC](https://forum.sienci.com/t/slb-flood-port-trigger-with-atc/27581/7 "2026-11-04T16:28:25Z")
Closed on November 4, 2026, 4:28pm UTC