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Tips on Setting GPIB Properties in Windows 95/98

Hardware: GPIB

Problem:
How do I set my GPIB properties in Windows 95/98?

Solution:
If you are new to GPIB, then do not make the mistake of confusing the primary address of your GPIB interface (i.e., your board) with the primary address of your GPIB device (i.e., your instrument). The primary address of the GPIB interface should always be 0, unless you have more than one GPIB board in your computer. If you make the mistake of giving your GPIB board the same primary address as your instrument, then you will get an EADR error (an addressing error) whenever you try to talk to your instrument.

The Termination Methods are the most common settings that you might change. There are three ways to terminate data messages:

• EOI (End or Identify) line
• EOS (End of String) character
• Byte Count

Byte count is ALWAYS used as a termination method, but you can also combine byte count with EOS, EOI, or both EOS and EOI. Many instruments will require an EOS character, usually linefeed (LF: \n, hex 0A, decimal 10) or carriage return (CR: \r, hex 0D, decimal 13), when you write data messages to them. In turn, they will terminate their own data messages to the GPIB board with the same EOS character. If you have more than one instrument and they each require a different termination method, then configure them individually in the Device Templates.

For example, if the user manual for your GPIB instrument at primary address 1 indicates that this instrument expects an EOS character (e.g., a linefeed) as the termination method, then you might use the following settings:

 

The default Device Name for the device at primary address 1 is "DEV1". The check in the box for Terminate Read on EOS (under Termination Methods) indicates that we will expect the instrument to terminate its messages with an EOS character. The EOS Byte box holds a value of 10, which is the decimal representation of the linefeed character.

Note: Even though you specify the EOS character here, you must still include that EOS character in any messages that you send to this instrument. The NI-488.2 driver will NOT automatically append a termination character to your message for you.

Also, if you expect to do any programming, then the preferred method of assigning these properties is to use the ibdev command (rather than using the ibfind command, which would make use of the information in the Device Templates). The ibdev command will override any settings in the Device Templates, making your code independent of the Device Template settings on any other computer, to which you might port your code.

You can edit the Interface Names used by the GPIB board and the Device Names used by your instruments, but it is highly recommended that you maintain the default Interface Name of "GPIB0" for your GPIB board.

Note: Please do not confuse the GPIB board's Interface Name with the instrument's Device Name. The Interface entry in the Device Templates is there to identify the GPIB board, to which your device is physically connected.

The default Device Names all follow the format "DEV#", where # is the primary address of the instrument. You can edit the device name in the Device Templates by left-clicking the "DEV#" entry from the Device Name list to select it, and then typing in the new name (8 characters maximum).

For example, if you want to change "DEV7" to "PWR_SUP", then you would left-click on "DEV7" to select it, and then type in "PWR_SUP" to give it a new device name.

Related Links:
Product Manuals: NI-488.2 User Manual
Developer Zone Tutorial: GPIB Hardware and Software Specifications
GPIB Support: GPIB Installation/Configuration Troubleshooter
Developer Zone Tutorial: Termination Characters for NI-VISA

Attachments:


- devtemp2.JPG
- devtemp3a.JPG


Report Date: 09/21/2006
Last Updated: 03/05/2008
Document ID: 41K6IQDW

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