ISO 20211:2015 pdf download.Space data and information transfer systems -Spacecraft Onboard Interface Services - Device Access Service.
Certain devices asynchronously emit values that arc stored by the service.To acquire such a ralue, an application provides a device logical identifier and a value identifier, which the service resolves in order to determine the stored value. The service then returns the most recently stored value. Optionally, the service may emit an indication to an application when an asynchronously emitted value from a device is acquired by the service.
Optionally, the service may indicate a timestamp associated with an acquired value. This timestamp indicates the time the value was generated by the device, emitted by the device, or acquired by the service (which is implementation-specific).
To command (i.e., send a value to) a device, an application provides a physical device identifier and a value identifier, together with the command value to be sent. The service resolves the physical device identifier in order to determine the DAP and a UT service, and if a response is generated by the device (as some devices do not generate a response to a command). The service maps information associated with the request onto the parameters of the protocol or the underlying service’s service-access-point, e.g., destination address and QoS parameters. The service then uses the DAP to command the device.
Optionally, the service may indicate a timestamp associated with an acquired value. This timestamp indicates the time the value was generated by the device, emitted by the device, or acquired by the service (which is implementation-specific).
To command (i.e., send a value to) a device, an application provides a physical device identifier and a value identifier, together with the command value to be sent. The service resolves the physical device identifier in order to determine the DAP and a UT service, and if a response is generated by the device (as some devices do not generate a response to a command). The service maps information associated with the request onto the parameters of the protocol or the underlying service’s service-access-point, e.g., destination address and QoS parameters. The service then uses the DAP to command the device.
