53A·519B · Data Acquisition Subsystem
OPT 1V · Add VXIbus Compatibility
53A-726 – Analog Cable, or
53A-780 · Hooded Connector

• High-speed 1 2-bit AID with on-card 16-channel multiplexer and memory for storage of 15,000 measurements
• Programmable rates up to 37,000 samples/second
• 16 differential voltage input channels
• Flexible triggering including pre- and post-event storage
• On-card preprocessing functions
• Extended Range for ±99V Input

The 53A-519B Data Acquisition Subsystem (DAS) implements, on a single card, the following functions associated with mufti-channel data acquisition:
– Multiplexer
– Ranging
– 12-bit Analog/Digital Converter (A/D)
– Microprocessor
– Memory
– Pre/Post Processing

The DAS, using an internal multiplexer, can select any one of 16 differential voltage input channels for measurement The user can select from one of two groups of bipolar input ranges (normal or extended), depending upon the application. Range selection within a given group is fully programmable, as is the measurement sampling rate. The DAS also allows an external sampling rate generator to be used.

The DAS can digitize input voltage levels, on a single channel basis, at rates of up to 37,037 readings per second to an accuracy of 12-bits. Randomly selected and multiplexed input voltage readings can be scanned and digitized at rates of up to 33,333 readings per second. Collected data is stored in an on-card 15,000 word (12-bit) memory. Since the DAS has a built-in microprocessor and memory, it can continue to collect data while the system controller is performing other tasks.

The on-card microprocessor provides full program control of the conditions under which data acquisition occurs, further freeing up the host computer for other tasks:
– A voltage trigger level may be programmed on each channel.
– Storage of digitized input voltage levels may be delayed until a programmed voltage level threshold is crossed.
– The DAS memory may be configured as a circular buffer to allow measurement data capture both before and after a trigger event (pre- and post-trigger).

Once a measurement sequence is completed, the system controller can request that each measurement taken be returned, or it can instruct the DAS to first pre-process the measurements before they are returned, or both. Pre-process commands are available for such functions as: average, mean, standard deviation, minimum, maximum. RMS, and true RMS value of measurements stored.

Built-in-Test Equipment (“BITE”) for the DAS is provided by a series of LEDs that indicate the status of the measurement in process, triggers, pre-processing, ranges, channel selection, and errors.

Normal Range: ±9.995V. ±0.9995V. ±0.09995V.
Extended Range: ±99.07V. ±9.907V. ±0.9907.


Delay Between Readings:
0 to 32,767 µsec, msec, seconds or hours.

Delay Between Measurement Cycles:
0 to 32,767 µsec, msec, seconds or hours (set of one or more channels repeatedly measured)

External Rate Generator:
Type Input. TTL, low true, 1 TTL Load.
Pulse Width, 50 nsec (min), 24  µsec (max).
Pulse Rate, 37037 Hz max.

Input Characteristics (each channel):
Number of Input Channels, 16.
Type Input. Differential.
Coupling, DC
Maximum Input. ±200V between any of the 32 input connections and analog ground; ±300V analog ground to earth ground.

Input Impedance (Normal Range):
Selected multiplexer channel,
>1 MOhm, shunted by < 100 pf. Unselected multiplexer channel, >1 MOhm, shunted by < 15 pF.

Input Impedance (Extended Range): >100 KOhms, shunted by < 15 pF

Effective Common Mode Rejection
(1 KOhm unbalance): 50 dB, DC to 1 KHz.

Maximum Common Mode:
Normal Ranges, ±5V dc
Extended Ranges, ±50V dc.

Cross Talk (channel to channel):
DC to 1 KHz, 10 KHz to 30KHz,


System Accuracy Drift:
High Range, ±30 ppm/C.
Mid Range, ±50 ppm/C.
Low Range, ±200 ppm/C.
Extended Ranges, ±25 ppm/C additional drift

Sample and Hold Aperture Time:
35 nsec

Aperture Time Uncertainty:
0.5 nsec

Calibration Cycle:
Every six months.

Measurement sequence proceeds when a Trigger command is received from the system controller.
Voltage, voltage on a specified channel is < or > programmed trigger voltage.
TTL, low for > 1 msec; loading, 1 TTL load.

Measurement Storage:
Pre-trigger; post-trigger; and center-trigger available.

Inhibit Input:
TTL, low true, 1 TTL load (prevents DAS from sampling when low).

Data Output:
Programmable. four decimal digits with sign and decimal point or 12-bit binary packed into two 8-bit bytes or blocked into records with a checksum.

Memory Storage:
15.000 twelve-bit readings.

Memory Organization:
Fixed Length Sequential or Circular Buffer.

Programmed By:
ASCII Characters.

Recommended Cable:
53A-726 Analog Cable or
53A-780 Hooded Connector

Available Option:
OPT 1V, add VXIbus compatibility.