Triggering

Triggering can be the most critical aspect of a data acquisition application. The DataShuttle/2000 supports a full complement of trigger modes to accommodate any measurement situation.

Hardware Analogue Triggering. Many data acquisition products claim analogue triggering, but rely on the PC to take readings and make a decision, which leads to uncertain and potentially long latencies. The DataShuttle/2000 uses true analogue triggering, whereby the trigger level programmed by the user, sets an analogue DAC, which is then compared in hardware to the analogue input level on the selected channel. The result is analogue trigger latency which is guaranteed to be less than 5 µs, significantly shorter than most data acquisition devices. Any analogue channel can be selected as the trigger channel, including built-in or expansion channels. The user can program both the trigger level, as well as the edge (rising or falling).

Digital Triggering (P1). A separate digital trigger input line is provided, allowing TTL-level triggering, again with latencies guaranteed to be less than 5 µs. Both the logic levels (1 or 0), as well as the edge (rising or falling), can be programmed for the discrete digital trigger input.

Digital Pattern Triggering (P2 or P3). The DataShuttle/2000 also supports digital pattern triggering, whereby the user can designate any of the digital input ports as the trigger port. The programmed digital pattern, including the ability to mask or ignore specific bits, is then compared to the actual input until a match is detected, after which the sequencer begins the scan sequence. Counter Triggering. Triggering can also be programmed to occur when one of the counters reaches, exceeds, or is within a programmed level. Any of the built-in counter/totalizer channels can be programmed as a trigger source.

Software-Based Triggering. Softwarebased triggering differs from the modes described above because the readings, analogue, digital, or counter, are interrogated by the PC to detect the trigger event, not in the hardware as described above. The advantage of this mode is to permit triggering based on more complex situations, such as on a specific temperature, which was derived from the acquisition of at least two analogue measurements, plus the calculation of the measured temperature using linearization algorithms.

Normally software-based triggering results in long latencies from the time that a trigger condition is detected, until the actual capturing of data commences. However, the DataShuttle/2000 circumvents this undesirable phenomenon by use of pre-trigger data. Specifically, when software-based triggering is employed, and the PC detects that a trigger condition has occurred, (which may be thousands of readings later than the actual occurrence of the signal), the DataShuttle/2000 driver automatically looks back to the location in memory where the actual trigger-causing measurement occurred. The acquired data that is presented to the user actually begins at the point where the triggercausing measurement occurs. The latency in this mode is equal to one scan cycle.

Pre- and Post-Triggering Modes. Six modes of pre- and post-triggering are supported, providing a wide variety of options to accommodate any measurement requirement. When using pre-trigger, the user must use software-based triggering to initiate an acquisition.

DataShuttle/2000 Signal Conditioning & Expansion Options
Product	Description	Capacity
DBK1	16-connector BNC interface module	16 connectors
DBK2	D/A voltage-output card	4 channels
DBK4	dynamic signal input card	2 channels
DBK5	current-output card	4 channels
DBK7	frequency input card	4 channels
DBK8	high-voltage input card	8 channels
DBK9	RTD measurement card	8 channels
DBK10	expansion-card enclosure	3 cards
DBK11A	screw-terminal card	40 terminals
DBK15	universal current/voltage input card	16 channels
DBK16	strain gage expansion card	2 channels
DBK17	simultaneous sample and hold card	4 channels
DBK18	low-pass filter card	4 channels
DBK20	general-purpose digital I/O card (screw terminals)	48 channels
DBK21	general-purpose digital I/O card (male DB37 connectors)	48 channels
DBK23	optically isolated digital-input module	24 channels
DBK24	optically isolated digital-output module	24 channels
DBK25	relay output card	8 channels
DBK32A	auxiliary power supply	±15 VDC @ 500 mA
DBK33	triple-output auxiliary power supply	±15 VDC @ 250 mA & ±5 VDC @ 1000 mA
DBK34A	DC to DC uninterruptable power supply	5 Amp Hrs @ 12V & 2.5 Amp Hrs @ 24V
DBK40	18-connector BNC interface	18 connectors
DBK41	analogue expansion enclosure	10 cards
DBK42	multi-purpose isolated signal-conditioning module	16 channels
DBK43	strain gage module	8 channels
DBK44	mutli-purpose isolated signal-conditioning card	2 channels
DBK45	simultaneous sample and hold card with low-pass filter	4 channels
DBK46	internal analogue output card	4 channels
DBK50	isolated high-voltage input module	8 channels
DBK51	isolated low-voltage input module	8 channels
DBK60	3-slot expansion module w/customizable panels	3 cards
DBK70	vehicle network interface module	4 cards
DBK80	differential voltage input card with excitation output	16 channels
DBK81	TC/mV card with screw-terminal connections	7 channels
DBK82	TC/mV card with screw-terminal connections	14 channels
DBK83	TC/mV card with external screw-terminal Pod and 3 ft. cable	14 channels
DBK84	TC/mV module with mini TC connector jacks	14 channels
DBK203	screw-terminal adapter board in rugged metal enclosure; P1/P2/P3, analogue and digital I/O expansion ports	120 terminals, P1, P2, P3