Simple AI-AO Benchmark VI for LabVIEW RT

There are a number of PID benchmarks in the NI KnowledgeBase for various controllers. This set of VIs will allow you to run PID benchmarks yourself. The VIs have been optimized for performance. In this example, an AI operation can be performed on a set of channels (channel 0 alone by default) followed by an AO operation on a set of channels (channel 0 alone by default).

There are three top-level VIs in this LLB. These VIs are intended to be run on a targeted RT controller. They do not have extra code for any host communication. Do not expect to achieve the maximum rates AND be able to transfer data to the host computer. The functionality of the three top-level VIs is as follows:

1) no-pid_benchmark.vi : Basic benchmark VI for a single PXI MIO device. Note the use of a For loop to require no front panel user interaction (controls or indicators) within the time-critical loop. This VI will execute for (iterations / scan rate) seconds. It is recommended to select a number of iterations such that it runs at the selected scan rate for at least a few seconds. If it completes with no error and the maintained real-time? LED indicator lights up, the scan rate you selected can be achieved.

2) no-pid_benchmark_twoboard.vi : This is a modified version of the no-pid_benchmark.vi that is set up to do AI on two devices synchronized with RTSI, and AO on one of them. It can be modified to use different AI channel sets for each board, or to use a separate board for AO.

3) no-pid_benchmark_whileloop.vi : This is a modified version of the no-pid_benchmark.vi that contains a control and indicator within the time-critical loop. The control is a numeric that controls the termination of the while loop, and the indicator shows the present number of iterations. Since this is a while loop, it will also terminate on an error, or if it loses real-time control. You must be more careful with this VI. Since it has to update and poll the UI, there are rates on the high-end of the scale that may work in the first example (for loop), but appear to cause this version to hang. Likely the VI is still running at this rate on the RT controller, but you will need to reset the controller before you can target it again.

Requirements

Filename: no_pid_aiao_benchmark.llb

Software Requirements

Application Software: LabVIEW Full Development System 6.0
Toolkits and Add-Ons: LabVIEW Real-Time Module, LabVIEW Real-Time Module 6.0
Language(s): LabVIEW

Hardware Requirements

Hardware Group: Multifunction DAQ (MIO)
Driver: Traditional NI-DAQ (Legacy) 6.9.2

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