RBRInstrumentFetching.h File Reference

Instrument commands and structures pertaining to on-demand data acquisition. More...

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Functions
RBRInstrumentError	RBRInstrument_fetch (RBRInstrument *instrument, RBRInstrumentLabelsList *channels, bool sleepAfter, RBRInstrumentSample *sample)
	Requests an “on-demand” sample set from the logger. More...

Detailed Description

Instrument commands and structures pertaining to on-demand data acquisition.

See also

https://docs.rbr-global.com/L3commandreference/commands/data-sample

Copyright

Copyright (c) 2018 RBR Ltd. Licensed under the Apache License, Version 2.0.

Function Documentation

RBRInstrument_fetch()

RBRInstrumentError RBRInstrument_fetch	(	RBRInstrument *	instrument,
		RBRInstrumentLabelsList *	channels,
		bool	sleepAfter,
		RBRInstrumentSample *	sample
	)

Requests an “on-demand” sample set from the logger.

Unlike streaming data/RBRInstrument_readSample(), fetched data is returned directly to the caller (independent of any RBRInstrumentSampleCallback defined in RBRInstrumentCallbacks.sample).

Because fetched samples are indistinguishable from streamed samples, this function may return a streamed sample, not a fetched sample, if the instrument is logging, streaming is enabled for the link over which the library is communicating with the instrument, and a streamed sample is produced by the instrument before the response to the fetch command.

For Logger3 instruments, the channels argument can be used to control which channels are fetched. This can be useful to limit the use of power-hungry sensors. If channels is not given as NULL, then readings will be requested from channels corresponding to the first RBRInstrumentLabelsList.count labels from the list. Otherwise, and for Logger2 instruments, readings will be fetched from all enabled channels.

Parameters

[in]	instrument	the instrument connection
[in]	channels	the list of channels to be acquired (may be NULL)
[in]	sleepAfter	whether the instrument should sleep after fetching
[in,out]	sample	the fetched sample

Returns

RBRINSTRUMENT_SUCCESS when a sample is successfully read

RBRINSTRUMENT_TIMEOUT when a timeout occurs

RBRINSTRUMENT_CALLBACK_ERROR returned by a callback

RBRINSTRUMENT_HARDWARE_ERROR when an invalid channel is requested

See also

https://docs.rbr-global.com/L3commandreference/commands/data-sample/fetch