NI-VISA automatically detects ports. You can view the list of ports with a VISA resource name control on the front panel or with the VISA Find Resource function. The maximum number of serial ports that NI-VISA supports on any platform is 256. The default numbering of serial ports is system dependent.

(Windows) NI-VISA supports interaction with parallel ports as well as with serial ports on your computer. You can use the VISA properties to communicate with parallel ports in the same way you communicate with serial ports.

Note   You may receive unexpected errors while attempting to write to a parallel port if you leave floating pins. Unlike the serial ports, parallel ports have pins that, if left floating, cause the port driver to assume that the attached device is busy (pin 11) or out of paper (pin 12). Ground pins 11 and 12 on the port to ensure that you can write successfully to the port.