A timestamp is recorded for each trigger event. A pre-trigger can be set so that data is recorded prior to the trigger event at the fast sample rate. The main uses for the ABA mode are applications that need a recorded history of a process, both leading up to and after the trigger event. For example, safety critical applications and quality testing can require continuous monitoring and high-speed recording in the event of a process or production failure.
While it is possible to pre-define the total number of samples to record so that the measurement card stops by itself, the most common use is likely to be where the measured data is continuously recorded to hard disk for audit trails. The maximum speed that data can be recorded to hard disk is 200 MBytes per second when using a RAID controller coupled to four S-ATA disks.
The slowest and fastest sampling rates that can be selected for the ABA mode are a function of the Digitizer/Oscilloscope card used. Strategic Test offers more than 80 different PCI cards. The minimum sampling rate is 1 kSamples per second on all cards, while maximum sample rates for different cards are : 16-bit resolution : 3, 1, 0.5, 0.25 MSamples per second; 14-bit resolution : 50 or 20 MSampes per second; 12-bit resolution: 200, 160, 100, 80, 50, 25, 10, 1 MSamples per second and 8-bit resolution : 200, 100, 50 MSamples per second. Cards are available with between 1 and 16 channels.
The ABA mode is included in an option bundle together with the Multiple Recording (memory segmentation), Gated Sampling (start/stop sample clock by external TTL signal) and the Timestamp option. The price for this combination is $990.