Using LabVIEW to write to a LCD display using a USB

[Gerardo09]

Hello,

I am trying to accomplish the task of using LabVIEW to communicate with an LCD display. All I need it to do is display text on the LCD screen. I have a set of command lines that I can use, but I am not sure as to how to send them directly to the LCD. Any insight would be helpful. Thank you in advnace.

[smercurio_fc]

You will need to provide a bit more information. What are these "command lines" that you have? Are these commands that you're supposed to execute a command prompt? Or, are they function calls that you would use in a C program (or similar)? Where does the USB come into play? What is the LCD that you're using? Do you have a link for it?

[jdpowell]

I've done something like that (with a Crystalfontz 635 USB-LCD).  I used the "virtual COM port" driver that comes with the unit and then used NI-VISA subVI's to talk to it.

-- James 

[Gerardo09]

I have established a connection through that TCP vi's and am now writing to the LCD through a dos prompt. Thank you for your help anyways.

[smercurio_fc]

That seems like a pretty "kludgey" solution. If you can provide more information (such as the actual model of the LCD) then perhaps we can suggest a cleaner solution.

[Jeremy_B]

Hi,

With the virtual com port driver, the USB connection will just look like a standard serial port.  You can use the VISA serial VIs to communicate over the port.  The CrystalFontz LCDs usually have documentation on how the communications protocol works.

Also, how did you establish a TCP connection to the LCD?   I know those LCDs don't natively support TCP/IP.

[smercurio_fc]

Just to be clear: The original poster never provided information as to which LCD they were using. In his reply James mentioned he has used a CrystalFontz LCD.

[Jeremy_B]

Woops, good point.  Its definitely a Monday 😉

Gerardo99,

What kind of LCD is it?

[Gerardo09]

You're right about my solution to the problem. Any additional ways to write to the LCD would be welcome. This is the link to the LCD: http://www.mini-box.com/picoLCD-20x2-OEM?sc=8&category=490. FYI, the LCD came by itself. All the documentation and software for the LCD display is downloaded from the website. I have tried reading all the manuals but it is unclear to me how to establish a direct connection through LabVIEW. Another note, the LCD does NOT show up as a virtual com port, and therefore I cannot use the VISA vis to write to the LCD. The LCD shows up as an HID in the device manager.

[smercurio_fc]

That LCD is a USB device. It seems to come with a server program that will accept TCP/IP connections. This seems to be the easiest way to get this up and running. You can launch the server program "USBLCDServer.exe" and then simply use the TCP/IP functions to connect to the server program and send commands. There is obviously a USB driver that comes with the device that gets installed, so if you're adventurous you can wade through the source code for that server program (which is available for download) to see how they communicate via the USB directly.

The LCD also has USART and I2C pins optional. It's not clear whether you have to order these options, or whether they come standard. This means you should be able to connect it to a serial port on a PC using the USART connections. You would need to check the voltages to make sure you don't need a transceiver.