Measurement group API reference

Important

Measurement group API was extended in SEP18 but this is still not documented in this chapter. Please check the said SEP for more information about the additional API or eventual changes.

The measurement group is a group element. It aggregates other elements like experimental channels (counter/timer, 0D, 1D and 2D or external attribute e.g. Tango) and trigger/gates. The measurement group role is to execute acquisitions using the aggregated elements.

A measurement group has a state attribute. The state indicates at any time if the measurement group is stopped, in alarm or moving. The state is composed from the states of all the elements involved in the measurement group. So, if one of the involved element (experimental channel or trigger/gate) is in moving or alarm state, the whole measurement group will be in that state.

The other measurement group’s attributes are:

timer

The name of the channel used as a timer.

integration time

Integration time to be used in the acquisition operation.

monitor count

Monitor count to be used in the acquisition operation.

acquisition mode

Acquisition mode to be used in the acquisition operation, either Timer or Monitor.

latency time

Latency time between two consecutive acquisitions in the same acquisition operation.

synch description

Describes the acquisition operation synchronization. It is composed from the group(s) of equidistant acquisitions described by the following parameters:

initial point
initial delay
total interval
active interval
number of repetitions

These parameters can be expressed in different synchronization domains if necessary (time and/or position).

moveable

Name of the master moveable.

Note: This attribute has been included in Sardana on a provisional basis. Backwards incompatible changes (up to and including its removal) may occur if deemed necessary by the core developers.

software synchronizer initial domain

Initial domain to be used by the software synchronizer.

If the initial parameter is described redundantly in the synchronization description i.e. both in the position and in the time domains, then this attribute will specify the one that will be used by the software synchronizer.

If the synchronization description does not contain value in this domain the software synchronizer will silently try to use the other one.

Note: This attribute has been included in Sardana on a provisional basis. Backwards incompatible changes (up to and including its removal) may occur if deemed necessary by the core developers.

The available operations are:

start acquisition()

Starts to acquire the measurement group.

start_acquisition()

stop()

stops the acquisition in an orderly fashion

abort()

stops the acquisition as fast as possible

release()

Release hung acquisition e.g. due to the hardware controller that got hung. You should first try stop/abort.