​
request_message

PX4 capability domain: request-system. PX4 mapping: MAV_CMD_REQUEST_MESSAGE. Request the target system(s) emit a single instance of a specified message (i.e. a “one-shot” version of MAV_CMD_SET_MESSAGE_INTERVAL).

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Request Params

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vendor
string
必填
Fixed value px4
​
device_id
string
必填
Target PX4 device ID
​
command_type
string
必填
Fixed value request_message
​
idempotency_key
string
必填
Idempotency key; repeated requests return the same command
​
timeout_seconds
integer
Timeout in seconds, range 0~300
​
payload
object
必填
Typed request payload for this command. Field names are generated from PX4 MAVLink XML labels, but callers do not send raw param1..param7 fields.
​
payload.message_id
number
Meaning: Message ID; maps to MAVLink parameter 1 in the PX4 frame.
​
payload.req_param_1
number
Meaning: Req Param 1; maps to MAVLink parameter 2 in the PX4 frame.
​
payload.req_param_2
number
Meaning: Req Param 2; maps to MAVLink parameter 3 in the PX4 frame.
​
payload.req_param_3
number
Meaning: Req Param 3; maps to MAVLink parameter 4 in the PX4 frame.
​
payload.req_param_4
number
Meaning: Req Param 4; maps to MAVLink parameter 5 in the PX4 frame.
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payload.req_param_5
number
Meaning: Req Param 5; maps to MAVLink parameter 6 in the PX4 frame.
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payload.response_target
number
Meaning: Response Target; maps to MAVLink parameter 7 in the PX4 frame.

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PX4 Frame Mapping

  • MAVLink command: MAV_CMD_REQUEST_MESSAGE
  • Command ID: 512
  • Default transport: COMMAND_LONG
  • Source XML: common.xml
  • Completion: COMMAND_ACK
  • Guard: real PX4 downlink is disabled by default; guarded mode requires explicit authorization and a ready transport.

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Create Response

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command_id
string
Platform command ID, used for follow-up queries
​
status
string
Acceptance status: ACCEPTED
​
accepted_at
string(datetime)
Command acceptance time (UTC)

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Query Response

​
command_id
string
Platform command ID
​
status
string
Execution status: ACCEPTED / DELIVERED / SUCCEEDED / FAILED / TIMED_OUT / UNMATCHED_RESPONSE
​
vendor
string
Vendor identifier; fixed value px4
​
device_id
string
Target PX4 device ID
​
command_type
string
PX4 command type
​
response_code
string
Mapped COMMAND_ACK.result value
​
response_message
string
PX4 acknowledgement summary
​
vendor_response
object
Raw PX4 acknowledgement summary, including MAVLink command ID and transport

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PX4 ACK Mapping

After sending the frame, the PX4 agent waits for COMMAND_ACK and correlates the response by command id. Disabled mode sends no frame and completes with a rejected lifecycle result. 
curl -X POST "/api/v1/open/downlink/commands" \
  -H "Content-Type: application/json" \
  -H "X-Api-Id: YOUR_API_ID" \
  -H "X-Api-Timestamp: YOUR_UNIX_SECONDS" \
  -H "X-Api-Nonce: YOUR_NONCE" \
  -H "X-Api-Signature: YOUR_SIGNATURE" \
  -d "{\"vendor\":\"px4\",\"device_id\":\"px4-real-1\",\"command_type\":\"request_message\",\"payload\":{\"message_id\":0,\"req_param_1\":0,\"req_param_2\":0,\"req_param_3\":0,\"req_param_4\":0,\"req_param_5\":0,\"response_target\":0},\"idempotency_key\":\"req-request_message-001\",\"timeout_seconds\":30}"

curl "/api/v1/open/downlink/commands/8cdb5bf3-8902-c5f7-f9aa-dc7fa0af1de0"

{
  "command_id": "8cdb5bf3-8902-c5f7-f9aa-dc7fa0af1de0",
  "status": "ACCEPTED",
  "accepted_at": "2026-06-15T00:00:00Z"
}