User manual

Programmer’s Guide Page 50 of 66
3.12. T3-style Data Readout
For the reading of timer data the AcqrsT3_readData routine should be used.
Control of the read parameters is passed through the input structure AqT3ReadParameters. The output format is
determined by these values as well as the type of module in use.
TC890 TOF modules use a direct read out of the modules data for maximum throughput. The PC does not have to
analyze the data coming from the module. The data are packed into 4-byte timer hits for each signal.
TC840 and TC842 modules have a two-phase readout. The Acqiris driver software in the PC analyzes the raw data as
read from the modules to derive the final timer results. These are presented in double floating point format or, for the
TC840 only, an integer count of the time in the specified time granularity of the module.
The TC890 data are coded on 32 bits as described below. This includes:
 Event on the channel 1 to 6, time relative to the common channel event
 Event on the common input, each common event are numbered, even the common event that are lost if the
internal Buffer is Full.
 Aux IO Event Marker.
 Switch marker.
[31] Overflow Indicates the time value is not good because the real-time counter reached its maximum value.
When the data is a marker this bit is also set „1‟.
if [30..28] = 0 to 6 => channel overflow
if [30..28] = 7 => marker
[30..28] DataType Type of the current data, Common channel, Channel number or Marker
0 for common (or channel 0)
1-6 for channel 1-6
7 denote the data is a Marker
[27..0] Time Channel 0: The value plus one is the number of hit of the common channel
Channel 1 to 6: The value is the time between the channel and the common.
Marker: Value=0 Switch marker: Switch from Auxiliary inputs (I/O Aux 1 or I/O Aux 2).
Value=1 Switch marker: Common channel Event count.
Value=2 Switch marker: Memory Full.
Value=16 Marker: Auxiliary inputs marker (I/O Aux 1 or I/O Aux 2).
3.13. Trigger Delay and Horizontal Waveform Position
When using a digitizer the user has 3 instrument setup variables with which to position the acquired waveform in
time:
sampInterval: the sampling interval (inverse of the sampling frequency)
nbrSamples: the number of samples to acquire
delayTime: the nominal trigger delay
Trigger
delayTime
sampInterval
nbrSamples