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Overcurrent Detection

Last Modified: May 2, 2019

Two NI-DAQmx Read/Write attributes/properties allow you to check for shorted channels. The first is OvercurrentChansExist. This attribute/property returns a Boolean true if one or more channels experience an overcurrent condition. The second is OvercurrentChans. This attribute/property returns an array of strings indicating which channels (if any) experienced an overcurrent condition. You must query the OvercurrentChansExist attribute/property before querying the OvercurrentChans attribute/property.

OvercurrentChansExist reads the overcurrent condition from the device and caches it in the driver. Subsequent reads of OvercurrentChans attribute/property will read the overcurrent channel information cached in the driver from the previous OvercurrentChansExist query.


For the NI 4610, use the AO.PowerAmp.Overcurrent attribute/property to check for shorted channels. On the NI 4610, AO.PowerAmp.Overcurrent detects the overcurrent condition for the specified channel and caches that information in the driver.

NI-DAQmx returns all data whether or not a short occurs. If your application requires overcurrent checking, it is recommended that you read the overcurrent attributes/properties after each call to Read/Write. Your program should discard questionable data or return a flag when the driver reports a short.

IEPE must be turned on for overcurrent detection to work (except for the NI 4322, NI 4610, NI 9219, and NI 9269). If IEPE is not turned on, an error is returned when OvercurrentChansExist is read.

Shorted current channels are known as short circuits. Overcurrent detection attributes/properties can be used to detect short circuits.

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