633 (Serial) Get Keypad presses but can't send any commands


New member
I have just hooked a 633 up to my WinXP machine, via the COM1 serial port... Using WinTest I receive correct notification of keypad presses but none of the other commands I attempt to send (backlight changes, change text on line 1 or line 2, etc...) work. Instead I receive a stream of error message along the lines of SendCharacter() sent 0 of 1 characters ...

Thoughts on what could be wrong?
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New member

I'm using the serial cable that came with the panel, going from the pin outs on the panel to the COM port on the back of my machine... in further testing I hooked up the Serial to USB converter (through the same cable) and it works fine on a virtual port... but I shouldn't need to use USB; I have 2 COM Ports open.

CF Tech

If the 633 works on a USB to serial converter (esentially just a 3rd serial port), and does not work on COM1, then I would think the 633 is OK and maybe the COM port on the motherboard has some trouble.

Do you have any other serial device that you can connect to COM1 so you can verify that the motherboard's COM port is working?
USB LCD Displays - Graphic and Character LCDs with a Keypad