An open current loop indicates that a load is not yet detected across the current output channel of your module.

The following NI-DAQmx Read/Write attributes/properties allow you to check for disconnected sensors:
  • OpenCurrentLoopChansExist—Returns a Boolean true if one or more channels are in an open current loop condition.
  • OpenCurrentLoopChans—Returns an array of strings that indicates which channels are in an open current loop condition.
    • Note You must query the OpenCurrentLoopChansExist attribute/property before you query the OpenCurrentLoopChans attribute/property.

    The OpenCurrentLoopChansExist attribute/property reads the open current loop condition from the device and caches it in the driver. The OpenCurrentLoopChans attribute/property reads the open current loop channel information that is cached in the driver from the previous OpenCurrentLoopChansExist query.

    Note
    • NI-DAQmx returns all data whether or not an open current loop occurs. If your application requires open current loop checking, it is recommended that you read the open current loop attributes/properties after each call to Read. Your program must discard questionable data or return a flag when the driver reports an open current loop.
    • For Analog Input devices with IEPE, the IEPE excitation current source must be enabled for open current loop detection to work. If IEPE is not turned on, an error is returned when OpenCurrentLoopChans is read.