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39: GPS Control ​

Read the GPS service state, control correction data, or request a GPS start mode. Use Position (message 15) for location data.

Applies to Viper devices only

Message fields

Fields specific to GPS Control. Operation sections below explain when each field is used.

FieldTypeDescription
GPS is onField 1bool

Status of the GPS, is it on?

Corrections EnabledField 2uint8

Request and apply correction data to the GPS, such as RTK.

  • 0 · Disabled
  • 1 · Full RTCM stream
Start ModeField 3uint8

Start mode of the GPS module.

  • 1 · Normal
  • 2 · Cold
  • 3 · Warm
  • 4 · Hot
GETMessage 39

Read GPS state

Return the current GPS and correction-service state, not a position fix.

Request

No payload fields are needed.

Request headers

MethodHeader 5
uint8required

Value 2 · GET

Request a service to be perform an action

Message IDHeader 1
uint32optional

Include a nonzero Message ID to correlate the reply.

Request data fields

GPS is onField 1
boolomitted

Status of the GPS, is it on?

Corrections EnabledField 2
uint8omitted

Request and apply correction data to the GPS, such as RTK.

  • 0 · Disabled
  • 1 · Full RTCM stream
Start ModeField 3
uint8omitted

Start mode of the GPS module.

  • 1 · Normal
  • 2 · Cold
  • 3 · Warm
  • 4 · Hot

Expected response (MT39)

GPS state

A successful GET returns GPS Control directly, with no separate success ACK. An unsuccessful request returns MT5 (ACK) with Status, not this payload.

Correlation, status and acknowledgment rules

Response data fields

GPS is onField 1
boolrequired

Whether the GPS service is on.

Corrections EnabledField 2
uint8required

Whether correction data is enabled.

  • 0 · Disabled: Disabled
  • 1 · Full RTCM stream: Full RTCM stream
Start ModeField 3
uint8omitted

Start mode is a SET input, not returned state.

  • 1 · Normal
  • 2 · Cold
  • 3 · Warm
  • 4 · Hot

Unsuccessful replies

Operation-specific causes. Codes are values of Status header 4, not payload fields.

7 Not Supported
Not Supported: the product or firmware does not support this operation.
SETMessage 39

Configure corrections and start mode

Enable correction data and/or restart the GPS in the requested boot mode.

Request

Use writable control fields, not the read-only GPS status field.

Request headers

MethodHeader 5
uint8required

Value 1 · SET

Request a service to be perform an action

Message IDHeader 1
uint32optional

Include a nonzero Message ID to correlate the reply.

Request data fields

GPS is onField 1
boolomitted

Read-only status. Sending this field in SET is rejected with Invalid Parameter (4).

Corrections EnabledField 2
uint8optional

Request and apply correction data to the GPS, such as RTK; this automatically controls the GPS module. Omitting this field sets API-enabled corrections to disabled, so a start-mode-only SET does not preserve the previous correction setting. Include 1 to keep API-enabled corrections on.

  • 0 · Disabled: Disabled
  • 1 · Full RTCM stream: Full RTCM stream
Start ModeField 3
uint8optional

If GPS is enabled, reboot it in this mode. If it is disabled, enable it with the requested state.

  • 1 · Normal: Normal
  • 2 · Cold: Cold
  • 3 · Warm: Warm
  • 4 · Hot: Hot

Expected response (MT5 - ACK)

For a request with a nonzero Message ID, successful SET returns an ACK, not GPS state. Use GET to read the current state afterward.

Correlation, status and acknowledgment rules · MT5 packet format

Unsuccessful replies

Operation-specific causes. Codes are values of Status header 4, not payload fields.

4 Invalid Parameter
Invalid Parameter: a read-only GPS status field or an unsupported start mode was supplied.
5 Invalid State
Invalid State: the correction service cannot be enabled in the current device state.
7 Not Supported
Not Supported: the product or firmware does not support this operation.

Message and field constants

Identifiers for this message type and its fields. See the operation sections above for rules and limits.