![loopback plugs loopback plugs](https://www.airborn.com.au/serial/db25loopback.jpg)
Make sure not to have VISA Test Panels and LabVIEW simultaneously open, or VISA will throw an access resource error (error code -1073807246 hex:0xbfff0072). Note: You can test communication in MAX VISA Test Panels or LabVIEW examples. If you are using RS-485, select the Advanced tab and make sure the Transceiver Mode is set correctly.
Loopback plugs serial#
For more information on serial settings, refer to the Help topic. Make sure the proper settings are selected and select Validate.
![loopback plugs loopback plugs](https://www.etwinternational.com/public/uploded/2477/17_7_loopback_connector_0.jpg)
It's been suggested that IBM's wrap plugs come as close to a standard as anyone's. For a parallel printer cable, I was able to buy an adapter from a D-25-M to a printer socket you could pull the socket from a discarded printer and wire it into the appropriate loopback if you can't buy an adapter. For serial cables, I use a standard commercial "Gender Changer" to connect the plug to one end of the cable while the other end is connected to the port. Most commercial loopback plugs are enclosed in a block of molded rubber, but it is easy to use a volt meter to test for continuity between pins.
Loopback plugs software#
It seems that most diagnostc software publishers now insist on using unique loopback configurations, probably so they can sell users another product.
![loopback plugs loopback plugs](https://www.stonewallcable.com/media/catalog/product/cache/1/image/512x512/9df78eab33525d08d6e5fb8d27136e95/s/c/sc3283_conn_w.jpg)
For serial and parallel ports, no additional electronics are necessary. Well, most loopbacks will take one signal and will return it on one or more other pins, perhaps two or three returns which the test program can distinguish. Diagnostic loopbacks are designed to allow a test program to send a signal on one pin and read its presence on another pin.