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image_start_capture

PX4 capability domain: camera-media. PX4 mapping: MAV_CMD_IMAGE_START_CAPTURE. Start image capture sequence. CAMERA_IMAGE_CAPTURED must be emitted after each capture. Param1 (id) may be used to specify the target camera: 0: all cameras, 1 to 6: autopilot-connected cameras, 7-255: MAVLink camera component ID. It is needed in order to target specific cameras connected to the autopilot, or specific sensors in a multi-sensor camera (neither of which have a distinct MAVLink component ID). It is also needed to specify the target camera in missions. When used in a mission, an autopilot should execute the MAV_CMD for a specified local camera (param1 = 1-6), or resend it as a command if it is intended for a MAVLink camera (param1 = 7 - 255), setting the command’s target_component as the param1 value (and setting param1 in the command to zero). If the param1 is 0 the autopilot should do both. When sent in a command the target MAVLink address is set using target_component. If addressed specifically to an autopilot: param1 should be used in the same way as it is for missions (though command should NACK with MAV_RESULT_DENIED if a specified local camera does not exist). If addressed to a MAVLink camera, param 1 can be used to address all cameras (0), or to separately address 1 to 7 individual sensors. Other values should be NACKed with MAV_RESULT_DENIED. If the command is broadcast (target_component is 0) then param 1 should be set to 0 (any other value should be NACKED with MAV_RESULT_DENIED). An autopilot would trigger any local cameras and forward the command to all channels.

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Request Params

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vendor
string
必填
Fixed value px4
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device_id
string
必填
Target PX4 device ID
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command_type
string
必填
Fixed value image_start_capture
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idempotency_key
string
必填
Idempotency key; repeated requests return the same command
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timeout_seconds
integer
Timeout in seconds, range 0~300
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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.
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payload.target_camera_id
number
Meaning: Target Camera ID; maps to MAVLink parameter 1 in the PX4 frame.
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payload.interval
number
Meaning: Interval, units s; maps to MAVLink parameter 2 in the PX4 frame.
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payload.total_images
number
Meaning: Total Images; maps to MAVLink parameter 3 in the PX4 frame.
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payload.sequence_number
number
Meaning: Sequence Number; maps to MAVLink parameter 4 in the PX4 frame.

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PX4 Frame Mapping

  • MAVLink command: MAV_CMD_IMAGE_START_CAPTURE
  • Command ID: 2000
  • 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
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status
string
Acceptance status: ACCEPTED
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accepted_at
string(datetime)
Command acceptance time (UTC)

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Query Response

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command_id
string
Platform command ID
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status
string
Execution status: ACCEPTED / DELIVERED / SUCCEEDED / FAILED / TIMED_OUT / UNMATCHED_RESPONSE
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vendor
string
Vendor identifier; fixed value px4
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device_id
string
Target PX4 device ID
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command_type
string
PX4 command type
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response_code
string
Mapped COMMAND_ACK.result value
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response_message
string
PX4 acknowledgement summary
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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\":\"image_start_capture\",\"payload\":{\"target_camera_id\":0,\"interval\":0,\"total_images\":0,\"sequence_number\":0},\"idempotency_key\":\"req-image_start_capture-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"
}