DSM

Details

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)

Notes

Models: Spektrum DSM2 and DSMX compatible receivers

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.

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.

Binding

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

Channel Order

Channel order is very important for DSM, and a common source of problems if not configured correctly.

By default the MULTI-Module will expect channels in the module's Expected Channel Order, and will convert them into TAER order automatically.

Unless you change the firmware on your MULTI-Module, your model should be configured with the channels assigned in AETR order, because this is the default Expected Channel Order.

If you change the firmware to expect a different channel order you must change the radio's default channel order and manually update any existing models.

See the Channel Order page for more details, including how to disable channel order remapping.

Option Value

Sets the number of channels for the receiver (3-12). The value is set automatically when using Autodetect Format or the Auto sub-protocol during binding.

Receiver Output Range

Either one of the methods below can be used to increase the output range. Usually one method is sufficient, but both methods can be combined to give even greater ranges or more customization if required.

Method 1 - Enable Max Throw

The easiest way to increase output ranges is by checking Enable max. throw in the model setup. This will increase the output range of all channels to 1024µs to 1976µs.

With Enable max. throw checked:

• The default weight of 100% will now give an output range of 1024µs to 1976µs

• A weight of 84% will give the Spektrum standard range of 1100µs to 1900µs

Method 2 - Extended Limits

Alternatively, output range can be increased by enabling Extended Limits in the model setup and configuring minimum and maximum output percentages for each channel in the Outputs.

This method allows each channel's range to be configured independently, and allows larger ranges than Enable Max Throw.

With Extended Limits enabled:

• A range of -100% to 100% will give an output range of 1100µs to 1900µs

• A range of -125% to 125% will give an output range of 1000µs to 2000µs

• A range of -130% to 130% will give an output range of 980µs to 2020µs

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

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+.

Telemetry Range

Some DSM receivers and many bind-and-fly (BNF) models with DSM receivers (e.g. E-flite UMX models) have 'fly-by' telemetry which has very limited range (less than 100' or 30m).

To avoid unnecessary 'telemetry lost' warnings when using a short-range-telemetry receiver, disable the telemetry warnings by checking the Disable telemetry alarms checkbox in the model's Telemetry configuration.

Throttle Kill

Throttle Kill is available on CH14 for models which need it (X-Vert, Blade 230S, etc.). The output value in is derived from the weight applied to CH14, which must be between -50% and -100%

• A weight of -50% gives 1100µs output

• A weight of -80% gives 980µs output

• A weight of -100% gives 904µs output

For example, CH14 is configured with a weight of -80%, switch SF as the source, and SF↓ as the switch

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

• When switch SF is on, the MULTI-Module sends 980µs on the throttle channel, killing the motors

Channel Assignment

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.