Event Notifications

The SDK delivers event data as one JSON object per callback. The top-level key identifies the event.

The examples use the camelCase field names returned by the C interface. Treat a missing field as its type’s default value.

`printStarted`

Reports the result of a print-start request.

Field	Type	Description
`success`	bool	High-voltage enable succeeded. `false` means startup failed
`message`	string	Additional status information. A successful result may also include this field when some heads report an abnormal state

{"printStarted":{"success":true}}

{"printStarted":{"message":"High-voltage enable failed"}}

Some successful results may include a message:

{"printStarted":{"success":true,"message":"Some print heads reported an abnormal state"}}

`upgradeStatus`

Reports upgrade processing state.

Field	Type	Description
`key`	string	Upgrade target
`status`	string	`parsing`, `progress`, `ready`, or `failed`
`message`	string	Progress, result, or failure information; may be present with any status

{"upgradeStatus":{"key":"SYSTEM","status":"parsing"}}
{"upgradeStatus":{"key":"SYSTEM","status":"ready"}}
{"upgradeStatus":{"key":"SYSTEM","status":"failed","message":"Invalid upgrade file"}}

For driver-board upgrades, status may be progress and message may contain a percentage such as "42%".

Status progression:

System upgrade: parsing → ready or failed
Driver-board upgrade: parsing → zero or more progress → ready or failed

For ready, a system upgrade file is ready for the next steps in the product manual. A driver-board upgrade has finished writing the firmware.

`triggerSignal`

Reports trigger-signal state.

Field	Type	Description
`status`	string	`on` or `off`

{"triggerSignal":{"status":"on"}}

`encoderSpeed`

Reports encoder pulse-rate information.

Field	Type	Description
`speed`	int	Encoder pulse rate in pulses per second (pps)
`pprA`	int	Encoder phase-A pulses per revolution (PPR)
`pprB`	int	Encoder phase-B pulses per revolution (PPR)

{"encoderSpeed":{"speed":123,"pprA":100,"pprB":200}}

`fpgaStatus`

Reports an FPGA status code.

Field	Type	Description
`code`	int	FPGA status code

{"fpgaStatus":{"code":12}}

`printComplete`

Reports that printing completed. This event has no fields.

{"printComplete":{}}

Handling Recommendations

Use the top-level event name to select the handler.
Use default values when optional fields are absent.
Ignore unknown event types so newer events remain compatible.
Do not perform long blocking work inside the callback.