LabVIEW Loopback Test for Serial Port

[G-Money]

Overview

This examples tests any serial COM port installed on the machine.

Description

This LabVIEW VI verifies the operation of your serial port hardware. You will need LabVIEW, standard 9-pin serial cable, and some wire or a paperclip. Connect the serial cable to your serial port and then short the transmit and receive pins of the cable with the wire. For an RS-232 cable you must short pin 2 to pin 3. For an RS-485 cable you must short pin 4 to pin 8 and pin 5 to pin 9.

Once everything is connected and your cable is shorted, run the Loopback.VI. This sends out a string and if your hardware is working correctly then you should receive that same message back.

Requirements

Hardware: PC/Laptop with Serial COM port (RS-232 or RS-422/485), Serial cable (RS-232 or RS-422/485) Software: LabVIEW Full Development System 2012 or compatible, NI-VISA

Steps to Implement or Execute Code

1. Connect the serial cable to COM port
2. Short circuit the transmit (Tx) and receive (Rx) pins of the serial cable. For an RS-232 port, wire pin 2 to pin 3. For an RS-485 port, wire pin 4 to pin 8 and pin 5 to pin 9
3. Check the COM number from NI MAX under Devices and Interfaces.
4. Enter the Port Number in the control
5. Enter the String to Write text
6. Run the VI

Additional Information or References

VI Code Screenshot*

 

*The NIVerified version of this code simply flattens the sequence structure for readability. Rewriting this to use the newer VISA Serial API is still recommended.

**The code for this example has been edited to meet the new Community Example Style Guidelines.**

[Khoa]

Hi there!

I see you used some vi's in the serial.llb file in C:\Program Files\National Instruments\LabVIEW 2010\vi.lib\Instr\serial.llb. But I wonder how can you find all of them because they do not appear on the functions palette. Do we have some way to get them all displayed in the function palette. I tried copying them to the user library folder but it doesn't work.

Thanks!

[crossrulz]

These VIs use the old serial port LabVIEW drivers.  They really should be rewritten using the VISA drivers instead.