Power Supply and Power Channel Considerations

Refer to Hardware Input and Output » DAQmx » Power in the LabVIEW Example Finder for examples that implement many of the following considerations.

Default Values

The following property values take effect when the task is committed or started.

Property Name Default Value
Pwr.IdleOutputBehavior Maintain Existing Value
Pwr.RemoteSense Local Sense
Pwr.OutputEnable True
Pwr.CurrentSetpoint 0.03A
Pwr.VoltageSetpoint 0 V

Configuring Voltage and Current Setpoints

Use the DAQmx Create Channel VI/function to set the current and voltage setpoints. Two properties reflect the current and voltage setpoints for a power channel, and are settable at runtime via the DAQmx Channel property node:

  • Pwr.Current.Setpoint —The constant output current, in amperes. If the load draws current greater than this value, output voltage is reduced and the device operates in constant current mode.
  • Pwr.Voltage.Setpoint —The constant output voltage, in volts.

    • Configuring and Reading Power Output States and Behavior

    Use the DAQmx Create Channel VI/function with the Pwr.OutputEnable property to enable or disable power channel output. At runtime, set this property via the DAQmx Channel property node.

    Use the DAQmx Channel property node with the Pwr.IdleOutputBehavior property to enable or disable power channel output when the task is uncommitted.

    Use the DAQmx Channel property node to read the Pwr.OutputState property and determine the channel state.

    Note Some DAQmx Read instances/functions return power channel samples in I16 format. These instance will always return a value of 0 for current and voltage while a power channel is disabled. Verify the power output state to validate a current or voltage sample value of 0.

    Detecting Auxiliary Power Errors

    Use the DAQmx Read property node to read auxiliary power supply errors. Two properties reflect the error state for auxiliary power.

    Note You must read AuxPowerErrorChansExist before you read AuxPowerErrorChans. Otherwise you will receive an error message.
  • AuxPowerErrorChansExist —Indicates if the device detected something is wrong with an auxiliary power supply.
  • AuxPowerErrorChans —Indicates a list of names of any auxiliary power supply error virtual channels.

    • Detecting Remote Sense Errors

    Use the DAQmx Read property node to read remote sense errors. Two properties reflect the error state for Remote Sense.

    Note You must read RemoteSenseErrorChansExist before you read RemoteSenseErrorChans. Otherwise you will receive an error message.
  • RemoteSenseErrorChansExist —Indicates if the device detected an error on a hardware or remote sense connection. You must disable the output and resolve the hardware connection issue to clear the remote sense error status for all channels in the task.
  • RemoteSenseErrorChans —Indicates a list of names of any remote sense error virtual channels.

    • Detecting Over-Temperature Errors

    Use the DAQmx Read property node to read over-temperature errors. Two properties reflect an over-temperature condition.

    Note You must read OvertemperatureChansExist before you read OvertemperatureChans. Otherwise you will receive an error message.
  • OvertemperatureChansExist —Indicates if the device detected an overtemperature condition in any virtual channel in the task. Reading this property clears the overtemperature status for all channels in the task.
  • OvertemperatureChans —Indicates a list of names of any overtemperature virtual channels.

    • Detecting Reverse Voltage Errors

    Use the DAQmx Read property node to read reverse voltage errors. Two properties reflect the reverse voltage error state of channel

    Note You must read ReverseVoltageErrorChansExist before you read ReverseVoltageErrorChans. Otherwise you will receive an error message.
  • ReverseVoltageErrorChansExist —Indicates if the device detected a reverse voltage error in any channel in the task. Reverse voltage error occurs if the local voltage is equal to the negative saturated voltage.
  • ReverseVoltageErrorChans —Indicates a list of names of any reverse voltage error virtual channels.

    • Configuring Remote Sense

    Use the DAQmx Channel property to set the Pwr.RemoteSense property.

    • DAQmx Read will return local voltage if Pwr.RemoteSense is configured to Local.
    • DAQmx Read will return remote voltage if Pwr.RemoteSense if configured to Remote.