Subscriptions

General

Subscribe

The communication protocol allows for subscribing to specific scale events. The corresponding information will then be sent when an event occurs.

Warning

Once a subscription is activated, the protocol can no longer be regarded as purely synchronous, since Response packets can be sent at any time. Make use of the message_id field to track Response/Request pairs.

The following events are available:

Info

Clicking on the response field tag will redirect you to the page where you can find more information about the selected response.

Event	Payload	Response field	Description
SUBSCRIBE_WEIGHT	Scale number (uint 32)	WeighingResult_ext	Get regularly updated with the weight from the scale
SUBSCRIBE_PARAMETER	None	ParameterDescription	Get updates when a parameter value is changed
SUBSCRIBE_DEBUG_LOG	None	log	Get all debug information from the scale
SUBSCRIBE_POWER_EVENTS	None	PowerEvent	Get updates over battery/ sleep modes
SUBSCRIBE_WIM	Scale number (uint 32)	wim_result	Get Weigh in Motion status
SUBSCRIBE_PRINTER	None	PrinterEvent	Get status updates from the printer

Unsubscribe

Event	Payload
UNSUBSCRIBE_WEIGHT	Scale number (uint 32)
UNSUBSCRIBE_PARAMETER	None
UNSUBSCRIBE_DEBUG_LOG	None
UNSUBSCRIBE_POWER_EVENTS	None
UNSUBSCRIBE_WIM	Scale number (uint 32)
UNSUBSCRIBE_PRINTER	None

Sequence diagram

The following diagram describes the sequence when subscribing to event X and event Y:

sequenceDiagram
    Client->>RedBox: Request subscription X
    RedBox-->>Client: Response status
    Client->>RedBox: Request subscription Y
    RedBox-->>Client: Response status
    loop Every x ms
        RedBox->>Client: Response subscription X
        RedBox->>Client: Response subscription Y
    end
    Client->>RedBox: Request unsubscription X
    RedBox-->>Client: Response status
    Client->>RedBox: Request unsubscription Y
    RedBox-->>Client: Response status

Sending subscription example

The code example below shows a client that is subscribed to the weight updates and power event from a Ravas RedBox.

Example

See also: protocol_send_basic_request() for an example how to send the request.

#define DEFAULT_SCALE_INDEX 0

void protocol_send_subs()
{
    protocol_send_basic_request(Request_Type_SUBSCRIBE_WEIGHT,          DEFAULT_SCALE_INDEX);
    protocol_send_basic_request(Request_Type_SUBSCRIBE_POWER_EVENTS,    DEFAULT_SCALE_INDEX);
}