0D channel API reference¶
The 0D experimental channel is used to access any kind of device which returns a scalar value and which are not counter/timer.
A 0D has a
state, and a
value attributes. The state indicates at any
time if the 0D is stopped, in alarm or moving. The value behaves exactly the
same as the accumulated value attribute.
The other attributes are:
Defines the computation type done on the values gathered during the acquisition. Three type of computation are supported:
Sum - the accumulation value attribute is the sum of all the data read during the acquisition. This is the default type.
Average - the accumulation value attribute is the average of all the data read during the acquisition.
Integral - the accumulation value attribute is a type of the integral of all the data read during the acquisition.
- current value
This is the current a.k.a. instant value of the experimental channel. If the current value attribute is read while the acquisition is in progress, it returns the last updated by the acquisition operation value (cache). When there is no acquisition in progress the current value read executes the hardware readout and returns an updated value.
- accumulated value
This is the result of the data acquisition after the computation defined by the accumulation attribute has been applied. This value is 0 until an acquisition has been started. After an acquisition, the attribute value stays unchanged until the next acquisition is started.
- accumulation buffer
This buffer is filled with the instant values read by the acquisition operation.
- time buffer
This buffer is filled with the timestamps of the instant values present in the accumulation buffer and it is also filled during the acquisition operation.
The available operations are:
- start acquisition(integration time)
starts to acquire the 0D with the given integration time
stops the 0D acquisition in an orderly fashion
stops the 0D acquisition as fast as possible