Protocol Number: 6 Autobind: No Channel Re-mapping: Yes Extended Limits: Yes Failsafe Support: No Receiver Match: Yes Telemetry: Yes - for TSSI and plugins Option Value: Number of channels (3 to 12), Enable Max Throw, Servo Refresh Rate (see Notes)


Models: Spektrum DSM2 and DSMX compatible receivers

Unless Channel Re-mapping is disabled, the radio model's channel order must match the Expected Channel Order of the MULTI-Module, which is AETR by default. See the Channel Order page for more details.

Autodetect Format

Autodetect Format (a.k.a. the Auto sub-protocol) allows the radio to negotiate the correct protocol (DSM2 or DSMX), the correct number of channels, and the optimal data rate with the receiver. Auto-detection relies on telemetry working between the radio and the receiver.

When binding, Autodetect Format is strongly recommended to ensure that the optimal configuration for the receiver is used.

If autodetection isn't working properly with your receiver (for example the number of channels is set incorrectly), you can un-check Autodetect Format and manually select the sub-protocol and number of channels.


For best results, set the sub-protocol to Auto for binding. During the bind process the receiver will inform the radio of the optimal configuration for sub-protocol, number of channels and refresh rate. When the bind ends the sub-protocol should have changed to one of the four DSM2 or DSMX options.

If binding using the Auto sub-protocol fails, and the sub-protocol remains on Auto, the radio was not able to negotiate the settings with the receiver. Try moving the radio closer or farther away from the receiver and trying again.

If you are unable to bind in Auto mode you can try all four sub-protocols manually.

When manually selecting the sub-protocol, your receiver may work correctly with more than one of them, or it may work correctly with one and erratically or not at all with others.

Take care when testing sub-protocols and ensure your model is safe (e.g. propellers off).

Option Value

  • A value of 3-12 will set the number of channels to that value

  • Adding 64 to the value will enable max throw (see Output Range)

  • Adding 128 to the value will enable 11ms refresh rates (see Servo Refresh Rate)

  • Adding 192 to the value will enable max throw and 11ms refresh rates

Output Range

  • Receiver output will match the Spektrum standard throw, 1100µs to 1900µs

  • If using PPM Mode ensure that the PPM_MIN_100 and PPM_MAX_100 settings in _Config.h match your radio's output

  • The maximum output is 1000µs to 2000µs when using an input weight of 125%

  • Maximum throw can be overridden using the Enable Max Throw setting. In this mode use a channel weight of 84% to achieve standard throw.

SAFE Select

To allow SAFE to be ON with a switch assignment you must remove the bind plug after powering up the RX but before turning on the TX to bind.

If you use Autodetect Format during binding the MULTI-Module will choose DSMX 11ms and Channels 1-7 (change channels to 1-9 if you wish to assign switch above channel 7).

In order to use the manuals diagram of both sticks 'Down-Inside' to set a SAFE Select Switch Designation, you must have Throttle and Elevator channels set to Normal direction but the Aileron and Rudder set to Reverse direction.

If setting up a new model with all channels set to Normal you can hold both sticks 'Down-Outside' to assign the switch with 5x flips. This has been tested on a Mode 2 radio.

Servo Refresh Rate

Servo refresh rate is 22ms unless 11ms is selected. The option to select the refresh rate when binding will be available in OpenTX 2.3.10+.

Throttle Kill

Throttle Kill is available on CH14 for models which need it (X-Vert, Blade 230S, etc)

  • If CH14 is between -100% and -50% the throttle output will be forced to the CH14 value minus 50:

    ThrottleOut=CH14Out50ThrottleOut = CH14Out - 50

An output value of -80% on CH14 will instantly stop the motors on an X-Vert by setting the throttle channel to -130%.

For example:

  • CH14 is configured with a weight of -80%

  • When the switch is off, CH14 is at 0%

  • When the switch is on, the MULTI-Module sends a value of -130% on the throttle channel: 8050=130-80 - 50 = -130

X-Vert -130% Throttle Kill on CH14 using switch SF

Channel Assignment




























Throttle Kill

The Channel Assignment table assumes the MULTI-Module's default Expected Channel Order, AETR, is being used on the radio.

If you have changed the MULTI-Module's Expected Channel Order to something other than AETR you need to adjust CH1 to CH4 accordingly. See the Channel Order page for more details.

Sub Protocols

0 - DSM2 1F

DSM2, resolution 1024, servo refresh rate can only be 22ms.

Note: 'DSM2 1F' was previously labelled as 'DSM 2 22ms'.

1 - DSM2 2F

DSM2, resolution 2048, servo refresh rate can be 22ms or 11ms. All servo outputs will be 22ms when more than seven channels are configured.

Note: 'DSM2 2F' was previously labelled as 'DSM 2 11ms'.

2 - DSMX 1F

DSMX, resolution 2048, servo refresh rate can only be 22ms.

Note: 'DSMX 1F' was previously labelled as 'DSM X 22ms'.

3 - DSMX 2F

DSMX, resolution 2048, refresh rate 22ms or 11ms. All servo outputs will be 22ms when more than seven channels are configured.

Note: 'DSMX 2F' was previously labelled as 'DSM X 11ms'.

4 - Auto

The Auto sub-protocol enables the radio to negotiate the correct settings for the receiver. Auto-negotiation is supported on OpenTX, erSkyTx, and er9x.

In OpenTX, Auto can be enabled by checking the Autodetect format box or selecting the Auto sub-protocol.

You must have telemetry enabled and working, and on erSkyTx you need to set the telemetry Usr proto to DSMx.