IviDmm Class Driver Overview
This instrument driver provides programming support for the IviDmm Class. The IviDmm class is designed to support the typical DMM as well as common extended functionality found in more complex instruments. The IviDmm class driver conceptualizes a DMM as an instrument that can measure scalar quantities of an input signal and can be applied to a wide variety of instruments. Typically the measured quantity is a voltage (AC and DC), current, or resistance. However, the IviDmm class driver can support instruments that measure other quantities such as temperature and frequency. The driver contains all the VIs that the IVI Foundation requires for the IviDmm specification. This driver requires NI-VISA and the IVI Compliance Package to be installed.
The IviDmm class is divided into a IviDmmBase capability group and several extension groups. The base capability group is used to configure a DMM for a typical measurement (which includes setting the measurement VI, desired range, desired resolution, and trigger source), initiating that measurement, and returning a measured value.
Many DMMs support measurement types that require additional parameters to be configured, such as the minimum and maximum frequency of the input signal for AC measurements. The IviDmm class defines extension groups for each measurement type that requires these additional parameters.
The IviDmm class also defines an extension group called IviDmmMultiPoint. The IviDmmMultiPoint extension group is used to configure DMMs that can acquire multiple measurements based on multiple triggers and take multiple measurements per trigger. This type of instrument used in conjunction with a scanner is typically used to implement a scanning DMM.
In addition, the IviDmm class defines extension groups that configure advanced settings such as auto-zero and powerline frequency, or return additional information about the current state of the instrument such as aperture time.
Use this driver to develop programs that are independent of a particular DMM. You can use this class driver with any DMM that has an IVI instrument specific driver that is compliant with the IviDmm class. The IviDmm class driver accesses the specific driver for your instrument using the configuration information you supply with MAX.
Extension Capability Groups
The IviDmm class driver identifies VIs and properties that belong to an extension group with the following abbreviations. Instrument specific drivers are not required to implement any of the extension capability groups. If you use VIs and properties that belong to extension capability groups, every instrument specific driver that you use must implement those extensions.
| Group Name | Abbreviation | Description |
|---|---|---|
| IviDmmACMeasurement | [AC] | Defines properties that configure additional settings for AC measurements. These properties are the minimum and maximum frequency components of the input signal. This extension group also defines VIs that configure these properties. |
| IviDmmAutoRangeValue | [ARV] | Supports DMMs with the capability to return the actual range value when auto ranging. |
| IviDmmAutoZero | [AZ] | Supports DMMs with the capability to take an auto zero reading. In general, the auto-zero capability of a DMM normalizes all measurements based on a Zero Reading. |
| IviDmmDeviceInfo | [DI] | Defines a VI and a set of properties that you can query to gain additional information about the instrument's configuration |
| IviDmmFrequencyMeasurement | [FREQ] | Supports DMMs that take frequency measurements. It defines properties that are required to configure additional parameters needed for frequency measurements. |
| IviDmmMultiPoint | [MP] | Supports instruments capable of acquiring measurements based on multiple triggers, and acquiring multiple measurements for each trigger |
| IviDmmPowerLineFrequency | [PLF] | Supports DMMs with the capability to specify the powerline frequency. |
| IviDmmResistanceTemperature Device | [RTD] | Supports DMMs that take temperature measurements using a resistance temperature device (RTD) transducer type. |
| IviDmmSoftwareTrigger | [SWT] | Supports DMMs that can initiate a measurement based on a software trigger signal. You can send a software trigger to cause the DMM to initiate a measurement. |
| IviDmmTemperatureMeasurement | [TMP] | Supports DMMs that take temperature measurements with a thermocouple, an RTD, or a thermistor transducer type. This extension group selects the transducer type. Other capability groups further configure temperature settings based on the transducer type. |
| IviDmmThermistor | [THM] | Supports DMMs that take temperature measurements using a thermistor transducer type. |
| IviDmmThermocouple | [TC] | Supports DMMs that take temperature measurements using a thermocouple transducer type. |
| IviDmmTriggerSlope | [TS] | Supports DMMs that can specify the polarity of the external trigger signal. It defines an property and a VI to configure this polarity. |