Before You Develop Your Driver

Being familiar with the instrument and its uses in actual applications helps you design a useful instrument driver application programming interface (API). Read the operating manual thoroughly. Learn how to use the instrument manually before you attempt developing interfaces to it. Use the instrument in an actual application to get practical experience. If the operating manual explains how to set up a simple test, do so.

Study the programming section of the instrument manual. Read the information on the instruction set to familiarize yourself with the available controls and functions and the organization of the features. Determine which instrument features you want to access for programmatic use. Test sending commands to the instrument to understand how the commands affect the operation of the instrument. Use one of the following tools to aid in interactive testing.

• Communicate with Instrument Utility—(Windows Only) Select the Devices and Interfaces option in Measurement and Automation Explorer (MAX) to communicate with IEEE-488.2 instruments. Use this utility to read, write, and query an instrument in a graphical environment. Use this utility to test instrument commands as you develop instrument drivers.
• VISA Interactive Control—NI-VISA includes the VISA Interactive Control (VISAIC) utility, which is called on all platforms that support the LabWindows/CVI Run-Time Engine. This utility provides access to all VISA functionality interactively in a graphical environment. Use this utility to test instrument commands as you develop instrument drivers.
• Instrument I/O Assistant—The Instrument I/O Assistant Express VI, available in the Express»Input or Express»Output palette, lets you send commands to an instrument, then view and parse the responses in real-time using steps. When you place the assistant on the block diagram, the interactive window appears. Though the assistant provides simple instrument control when an instrument driver is unavailable, you can use it as an interactive tool as well.

• Paths: Check Use default.
• (Recommended) Front Panel: Select the Modern 3D style for use for new VIs.
• Block Diagram: Check Use transparent name labels..
• Block Diagram: Uncheck Place front panel terminals as icons.
• Block Diagram: Uncheck Enable automatic error handling in new VIs.
• Block Diagram: Uncheck Enable automatic error handling dialogs.
• Environment: Check Use default colors.
• Environment: Check Use default font.
  

Setting these user options before you create new VIs helps you create an instrument driver that is consistent with the look and feel of other certified instrument drivers. For example, use the default application font to ensure cross-platform compatibility. If you create a VI without these options, verify that the VI complies with the settings listed above.