diff --git a/common/source/docs/common-auxiliary-functions.rst b/common/source/docs/common-auxiliary-functions.rst
index 0e0008de6e..6b4b87e5da 100644
--- a/common/source/docs/common-auxiliary-functions.rst
+++ b/common/source/docs/common-auxiliary-functions.rst
@@ -280,6 +280,8 @@ Supported Features
 +----------------------+----------------------------+----------+---------+---------+
 |        176           | VTOL Fwd Throttle disable  |          |    X    |         |
 +----------------------+----------------------------+----------+---------+---------+
+|        177           | Mount LRF Enable           |    X     |    X    |    X    |
++----------------------+----------------------------+----------+---------+---------+
 
 Intended as continuous PWM range control inputs:
 
@@ -569,6 +571,7 @@ Other functions are:
     Camera Image Tracking                 Activate Camera Image Tracking (only supported by ViewPro camera gimbals)
     Camera Lens                           Select the active camera lens (only supported by ViewPro camera gimbals)
     VTOL Fwd Throttle disable             Overrides use of forward throttle in VTOL modes
+    Mount LRF Enable                      Enable(switch high) ranging updates
     ROLL Input                            ROLL input channel. (replaces RCMAP)
     PITCH Input                           PITCH input channel. (replaces RCMAP)
     THROTTLE Input                        THROTTLE input channel. (replaces RCMAP)
diff --git a/common/source/docs/common-viewpro-gimbal.rst b/common/source/docs/common-viewpro-gimbal.rst
index 34d76cca46..b8cd12ef9d 100644
--- a/common/source/docs/common-viewpro-gimbal.rst
+++ b/common/source/docs/common-viewpro-gimbal.rst
@@ -69,6 +69,11 @@ Control and Testing
 
 See :ref:`Gimbal / Mount Controls <common-mount-targeting>` and :ref:`Camera Controls <common-camera-controls>` for details on how to control the gimbal using RC, GCS or Auto mode mission commands
 
+IR Rangerfinder Control
+=======================
+
+Some versions of the ViewPro Gimbals have an IR rangefinder that displays range in the OSD. This continuous ranging updating can be disabled using an RC switch whose ``RCx_OPTIONS`` is set to "177".
+
 Testing Video Streaming
 =======================