Fred:
> On 4/25/22 10:17, karl@??? wrote:
...
> I am using the DLP-TXRX-G usb/serial adapter with a transistor to invert
> the mouse output. The mouse has an active high output and the dlp rx
> input is active low.

This one:
http://www.dlpdesign.com/usb/txrx.php
seems to be ttl, not rs232 levels/signals.

> I forgot to say in the previous message that x and y movement and
> buttons 1 and 3 all work normally. Only the middle button doesn't work.

Well, half a victory!

> I have some hardware that would be fairly easy to have read in the mouse
> signals and display the bytes. I will do this over the next few days
> and it should be possible to determine the exact protocol.

Nice.

Regards,
/Karl Hammar