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GPIB to Serial Converter G Mode Loopback Test in MAX

Primary Software: Driver Software>>NI-488.2
Primary Software Version: 2.4
Primary Software Fixed Version: N/A
Secondary Software: N/A
Hardware: GPIB>>External Controllers/Convertors>>GPIB-232CT-A, GPIB>>External Controllers/Convertors>>GPIB-485CT-A

Problem:
I have a GPIB to Serial converter and want to do a loopback test on the serial port of this converter. Is there an easy way of doing this without using IBIC?

Solution:
The GPIB to Serial converters have two modes. In S mode they act as an interface from your computer to the GPIB Bus. The device acts as the controller on the GPIB bus in this mode. In G mode it acts differently. It is an instrument on the GPIB bus and is the controller on the Serial bus side.

To do a loopback test in G mode, set the last dip switch to the ON position (G mode). The GPIB address needs to be the lower of any two consecutive addresses that are not currently used on the GPIB bus. So if addresses 5 and 6 are not used on the bus, the converter should be set to address 5. The far left switch designates the least significant bit of the address.  To test communication with the device:
  1. Select Start»Program Files»National Instruments»Measurement & Automation Explorer (MAX)

  2. Select the GPIB device on the computer under Devices and Interfaces.

  3. Select Scan for Instruments, you should have two more instruments on the bus. The lower address is the GPIB portion of the converter. You can give it commands to set parameters for the serial port. The high address, by default, is the interface to the serial port. Sending strings to this instrument will result in the command being transmitted to the serial bus.

  4. Attach the proper serial cable to the serial port and short the correct pins for a loopback test.

  5. Select the serial port interface instrument from the GPIB folder.

  6. Right click on the instrument and select Communicate with Instrument.
You can now write and read from the instrument. When reading, you should see the last string that was written to the serial port.

Related Links:
Product Manuals: GPIB-232/485CT-A User Manual
KnowledgeBase 2U2JRRLD: How Do I Set the Serial Port Characteristics on the GPIB to Serial Hardware in G Mode?
Developer Zone Tutorial: How to Do a Serial Loopback Test

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Report Date: 04/06/2006
Last Updated: 05/30/2008
Document ID: 3W5FNHG2

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