SF Inst. Trim moves trims outside max. trim

[mha1]

Is there an existing issue for this problem?

• I have searched the existing issues

What part of EdgeTX is the focus of this bug?

Transmitter firmware

Current Behavior

SF Inst. Trim moves trims outside max. trim

Expected Behavior

Limit trims to min/max trims

Steps To Reproduce

1. Set up SF Inst. Trim
2. Hold Rudder Stick slightly out of center
3. Activate SF Inst. Trim multiple times and observe rudder trim

WhatsApp.Video.2026-01-30.at.10.40.20.mp4

Version

2.12.0-RC

Transmitter

RadioMaster TX15

Operating System (OS)

No response

OS Version

No response

Anything else?

2.12.0-rc2

[philmoz]

That's how it works - instant trim can adjust up to the extended trim limit (+/- 512).

[mha1]

Is it ok that the trim marker leaves the trim bar?

[3djc]

First point: instant trim can adjust up to the extended trim limit (+/- 512) ?
Likely yes, you don't want your instant trim be limited because you did not preselect the right trim limits

Second point: Is it ok that the trim marker leaves the trim bar?
Likely yes, you needed more trims than your current trims limits, display will show you that until you select a right trim settings

Put your trim mode to extented, it will display correctly

[mha1]

Thanks for the info. Shouldn't Inst. Trim respect the Extended Trims setting?

[3djc]

Clearly not, if you are in flight and cannot instant trim because you didn't set extended because you couldn't know you would need it could lead to crashses. I personnaly think instant trim is inherently dangerous, but I'm side tracking

[mha1]

Please help me understand the logic behind this. If you don't have Inst. Trim active (= default) and Extended Trims not active (= default) using trims Tx won't let you go beyond 25% trim. Why should Inst. Trim allow more without Extended Limits active?

[pfeerick]

The primary purpose / reason for existence of the Instant Trim function is and has always been for maiden flights. As such, it can and does trim to the full extent possible, period.  This is a documentation issue only IMO. The alternate is a drastic change in behaviour in this special function which has operated like this for over 10 years. 

[mha1]

The primary purpose / reason for existence of the Instant Trim function is and has always been for maiden flights. As such, it can and does trim to the full extent possible, period. 

This is a documentation issue only IMO. The alternate is a drastic change in behaviour in this special function which has operated like this for over 10 years.

thanks for clarifying