How the GTX2200/GC2200 Series Timer Counter Gate works

Knowledge Base Article # Q200170

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Summary A description of the GTX2200/GC2200 Gate functionality
The GTX2200 and GC2200 series timer/counter allows the user to set a gate time through either the software front panel or through a API call GxCntSetGateTime().

The gate will stay open until one full period of the input signal has completed.

If the gate time is set to a value that is less than one period of the input signal, then the gate will actually remain open until one signal period has completed. This is why a valid measurement is obtained when the gate time is set to a value less than the input signal period.

This behavior also explains the "plus up to one signal period" in the gate time specification (GTX2200 Datasheet). If the gate time expires in between a period of the input signal, the gate will remain open until that cycle (period) completes.

An example of this is as follows:
If the gate time is set to 500 uS, and the input signal's period is 200 uS, the gate will actually close at 600 uS, after the 3rd cycle has completed (it will not close mid-cycle at 500 uS).
How the GTX2200/GC2200 Series Timer Counter Gate works
Therefore the function of the gatetime is to allow the user to force the instrument to oversample an input signal. The instrument does not allow the user to select a gate time that will result in a closure part way through a cycle of the measured signal.

The Measurement Timeout can be set by using the API function call GxCntSetMeasurementTimeout() to make sure that a very slow signal will not cause unnecessary delays in your program.
Article Date 12/22/2009 9:43:28 AM
Keywords GTX2200, GTX2210, GTX2220, GTX2230, GC2200, Timer Counter, Gate

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