TetrAMM and FX4 Acquisition Modes

The TetrAMM and FX4 can be used in 8 different acquisition modes, depending on the values of the TriggerMode and AcquireMode records. The following table describes these modes. Note that AcquireMode=Single is completely equivalent to AcquireMode=Multiple and NumAcquire=1, so the table does not list AcquireMode=Single.

Note that the TetrAMM supports triggering and gating modes in the firmware, using the commands shown in the table below. The FX4 does not support triggering or gating for ADC acquisition. However, it does support streaming of the digital input signals while also streaming the data. Each ADC measurement and each transition on the digital input has a precise timestamp. The EPICS support streams the first digital input signal, and does the triggering and gating operations in the driver software, using the digital input transitions and the timestamps.

TriggerMode	AcquireMode	Description	TetrAMM commands
Free Run	Continuous	Values are acquired continuously and are averaged each time the AveragingTime is reached.	NRSAMP=ValuesPerRead, NAQ=0, TRG:OFF
Free Run	Multiple	Data is acquired for the AveragingTime. This is repeated NumAcquire times and then acquisition stops. The plugins will be called NumAcquire times, each time with NumAverage samples.	NRSAMP=ValuesPerRead, NAQ=0, TRG:OFF
Ext. Trig.	Continuous	A fixed number of samples is acquired starting on each rising edge of the external trigger input. AveragingTime must be set to a value less than the time between trigger pulses.	NRSAMP=ValuesPerRead, NAQ=AveragingTime/1e5/ValuesPerRead, TRG:ON
Ext. Trig.	Multiple	A fixed number of samples is acquired starting on the first rising edge of the external trigger input. This repeats NumAcquire times and then acquisition stops. ValuesPerRead must be set to a value less than AveragingTime/1e5.	NRSAMP=ValuesPerRead, NAQ=AveragingTime*1e5/ValuesPerRead, TRG:ON
Ext. Bulb	Continuous	Samples are acquired while the external trigger input is asserted. On each trailing edge of the external trigger signal the plugins are called. ValuesPerRead must be set to a value less than (external trigger asserted time * 1e5). AveragingTime is ignored in this mode.	NRSAMP=ValuesPerRead, NAQ=0, TRG:ON
Ext. Bulb	Multiple	Samples are acquired while the external trigger input is asserted. On each trailing edge of the external trigger signal the plugins are called. This is repeated NumAcquire times and then acquisition is stopped. ValuesPerRead must be set to a value less than (external trigger asserted time * 1e5). AveragingTime is ignored in this mode.	NRSAMP=ValuesPerRead, NAQ=0, TRG:ON
Ext. Gate	Continuous	Samples are acquired while the external trigger input is asserted. When NumAverage samples have been acquired the plugins are called. The actual averaging time between calling the plugins will be longer than AverageTime, and is controlled by the duty cycle of the external gate signal. The trailing edge of the gate pulse is ignored in this mode. ValuesPerRead must be set to a value less than (external trigger asserted time * 1e5).	NRSAMP=ValuesPerRead, NAQ=0, TRG:ON
Ext. Gate	Multiple	Samples are acquired while the external trigger input is asserted. When NumAverage samples have been acquired the plugins are called. The actual averaging time between calling the plugins will be longer than AverageTime, and is controlled by the duty cycle of the external gate signal. When the plugins have been called NumAcquire times then acquisition is stopped. Note that the actual number of gate pulses received will be > NumAcquire, and is also controlled by the duty cycle of the external gate signal. The trailing edge of the gate pulse is ignored in this mode. ValuesPerRead must be set to a value less than (external trigger asserted time * 1e5).	NRSAMP=ValuesPerRead, NAQ=0, TRG:ON