Data Acquisition (DAQ) and Control from Microstar Laboratories

DAPL Command Benchmarks

Technical Note TN-164 Version 2.4

Benchmarks are valuable tools for evaluating the maximum sampling speed of certain types of applications and for comparing the performance of different Data Acquisition ProcessorsTM. Simple applications were written with a selected set of DAPL commands to provide performance benchmarks. These benchmarks can be helpful when deciding which Data Acquisition Processor is best for an application.

Following is an overview of the benchmark procedures, the hardware and software configuration used during testing, and a benchmark summary. A table presents benchmark results for various Data Acquisition Processors.

Test Procedures

Each DAPL application used to benchmark a command consisted of an input procedure sampling one channel. A 100 Hz square wave was applied to the inputs.

The benchmarks were run by setting the TIME command in the input procedures as low as possible without causing input channel pipe overflow. The DAPL command DISPLAY MEM was used to check memory use on the Data Acquisition Processor. Stable memory use indicated that the processing procedure could keep up with the input procedure sample rate. There were some normal fluctuations in memory use as the Data Acquisition Processor filled and emptied buffers. However, the maximum memory use reported by DISPLAY MEM did not increase over time.

Most applications transfer data to the PC. PC transfer tasks were replaced with PCOUNT tasks during the benchmark tests. This enables comparisons between Data Acquisition Processors without generating large volumes of data output. Since data values are not sent to the PC, the benchmarks are independent of computer performance.

Test Accuracy

The results of the benchmark tests are accurate to within five percent. TIME commands greater than 20 microseconds were changed in 1.0 microsecond increments. TIME commands less than 20 microseconds were changed by the smallest increment permitted by each Data Acquisition Processor (0.1 microseconds for DAP 4200a/526; 0.05 microseconds for DAP 4000a, DAP 840/103, DAP 5000a/526, DAP 5016a/527, and DAP 5200a/626; and 0.02 microseconds for DAP 5400a).

Table: Benchmark Results - Sampling Rate in kS/s

Description 4000a & 840/103 4200a/526 5000a/526 & 5016a/527 5200a/626 5400a/627
AVERAGE 100 1111* 1667* 1667* 1667* 7547
AVERAGE 10 833* 1667* 1667* 1667* 6667
LIMIT & WAIT 1000* 1667* 1667* 1667* 7143
INTEGRATE 189 500 1667* 1667* 3478
RMS (100) 526 1250* 1667* 1667* 5940
SCALE 204 526 1428* 1667* 2963
21 taps decm. 5
476 1000* 1667* 1667* 4706
101 taps decm. 5
179 357 909* 1667* 2667
FIRFILTER 21 taps 132 286 769** 1667* 2000
FIRFILTER 101 taps 40.3 80.0 208 869* 740
FFT 1024 pts. 90.9 213 1052* 1667* 2222
FFT 16384 pts. 68.9 178 556** 1428* 1081
THERMO 66.7 163 909* 1052* 1739
PID 42.6 188 555* 1000** 941

NOTE: Numbers that appear in BOLD represent the maximum DAP sample rate. For the DAP 5400a, the sample rates are obtained by performing the same command on each of the eight simultaneously sampled channels.
* Digital input used to achieve minimum TIME
** Digital input used for DAP 5016a


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