Update README.md (#14266)

Updated section on shutter position with info on the automatic calibration's reliance on the actuator's automatic stop message, and that for older actuator's manual setting of shutterRun is required.

diff --git a/bundles/org.openhab.binding.openwebnet/README.md b/bundles/org.openhab.binding.openwebnet/README.md
index c75c33c3ddf634e280a9c7fc1660978fa53b6c04..c36b44150a0f1236b736b7c5396466fa241a9a82 100644 (file)
--- a/bundles/org.openhab.binding.openwebnet/README.md
+++ b/bundles/org.openhab.binding.openwebnet/README.md
@@ -257,8 +257,15 @@ OPEN command to execute: *5*8#134##
 
 #### `shutter` position
 
-For Percent commands and position feedback to work correctly, the `shutterRun` Thing config parameter must be configured equal to the time (in ms) to go from full UP to full DOWN.
-It's possible to enter a value manually or set `shutterRun=AUTO` (default) to calibrate `shutterRun` automatically: in this case a _UP >> DOWN >> Position%_ cycle will be performed automatically the first time a Percent command is sent to the shutter.
+For Percent commands and position feedback to work correctly, the `shutterRun` Thing config parameter must be configured equal to the time (in ms) to go from full UP to full DOWN. It's possible to enter a value manually or set `shutterRun=AUTO` (default) to calibrate `shutterRun` automatically.
+
+_Automatic calibration of `shutterRun`_
+
+If `shutterRun` is set to AUTO a _UP >> DOWN >> Position%_ cycle will be performed automatically the first time a Percent command is sent to the shutter. The binding then relies on the _STOP_ command sent by the actuator at the stop time set in the actuator's advanced configuration in the My Home Suite. Therefore the binding's automatic calibration of `shutterRun` only works correctly if the stop time is set to the time the shutters need to go from full UP to full DOWN. 
+
+Older actuators that come without an ID and do not support advanced configuration via the My Home Suite have a fixed stop time of 60 seconds. In this case auto calibration of the binding cannot be used and `shutterRun` has to be set manually.
+
+_Notes on `shutter` position_
 
 - if `shutterRun` is not set, or is set to `AUTO` but calibration has not been performed yet, then position estimation will remain `UNDEF` (undefined)
 - if `shutterRun` is wrongly set higher than the actual runtime, then position estimation will remain `UNDEF`: try to reduce shutterRun until you find the right value