Measurement Computing TP ADAC-32 rev.1.0 - Manual (Page 8)

ADAC PCI Series TP ADAC-32 Driver 5
5.1.1 A/D Internal Burst Triggering
For burst acquisition, TestPoint’s A/D Objects “StartA/D” or “AcquireA/D” rate parameter can be used to
program the on-board pacer clock to the rate at which burst scans are initiated. The rate parameter is the
exact frequency at which burst scans are initiated, i.e. if the rate were set to 1000 and the Channel(s) = 0, 1,
2, 3, 4, 5, 6, 7, the total number of A/D samples obtained in one second would be calculated as (8 channels
X 1000Hz.).
5.1.2 A/D External Burst Triggering
In burst mode acquisition, the (ADTGIN) input can be used to initiate a burst scan, each low to high
transition of the (ADTGIN) input will initiate a another burst scan.To select this option, set TestPoint’s
A/D Objects “StartA/D” or “AcquireA/D” rate parameter to 0 and “Set A/D trigger Immediate”.
5.2 A/D TRIGGERING METHODS
The TestPoint A/D Objects “StartA/D” and “AcquireA/D” “Set A/D trigger digital” allows an external
event to start the acquisition. In addition the TestPoint “Other A/D command, PRETRIGGER(value)” is
used to enable About mode acquisition when Set A/D trigger digital is enabled. In about mode the specified
number of PRETRIGGER(samples) is collected before the a trigger event and the rest of the samples after
the trigger. The external signal edge that triggers defaults to falling edge, but may be changed in the adac-
tp.ini file using the ADAC Config program to either EXT_FALLING_EDGE or EXT_RISING_EDGE.
Note: The Trigger Source signal may also be output to the terminal connector/panel, to do this you must
modify the adac-tp.ini file using the ADAC Config program and set the TrigOutput setting to ENABLED
5.2.1 Post Triggering
In non-burst mode acquisition, the (ADTGIN) or (DATGIN) input can be used to start the acquisition, a
low to high transition of the ADTGIN connection will start the process. To do this set the TestPoint’s A/D
Objects “StartA/D”, “AcquireA/D” or “StartD/A” to “Set A/D Trigger Digital” just prior to each
“StartA/D”, “AcquireA/D” or “StartD/A”call.
5.3 D/A TRIGGERING METHODS
The TestPoint A/D Objects “StartD/A” can have an external event to start the acquisition as defined by the
D/A setting in the adac-tp.ini file. Using the ADAC Config program to modify the D/A trigger settings, the
trigger mode and edge may be configured.
5.4 A/D AND D/A CLOCKING METHODS
For non-burst acquisition, the rate parameter that TestPoint’s A/D Objects “StartA/D”, “AcquireA/D” and
StartD/A calls provide, is the rate in Hz at which the A/D or D/A conversions are clocked. For the A/D, the
rate is a multiple of the number of channels specified in the Channel(s)= parameter, i.e. if the rate were
equal to 1000 and the Channel(s) = 0, 1, 2, 3, 4, 5, 6, 7; the actual A/D clocking would be 8000 Hz, 1000
Hz per channel.
ADAC Series PCI boards also support an external clocking input connection that may be used to clock the
A/D conversions. To select the external clock input as the A/D clocking source, set the rate parameter in
TestPoint’s A/D Objects “StartA/D”, “AcquireA/D” or StartD/A to “0”. If the rate parameter is set to 0 the
signal edge that triggers defaults to falling edge, but may be set by the TestPoint “Other A/D command,
EXTCLKEDGE(value) as EXT_FALLING_EDGE or EXT_FALLING_EDGE”. The EXTCLKEDGE
must be issued just prior to each Start or Acquire command.