Cheap Idea for a DRO

[BillTodd]

I like the idea of using a PC or laptop for the readout's and controls. I've never really got into VB programming but I'm quite happy with PIC assembler (not C though...that scares me).

You should be able to understand the code easily enough :)

I was told that VB interface to RS232 Com Port is not that well documented and is a bit tricky?

Doesn't seem tricky to me - maybe I've already done all the head-on-wall banging necessary ;)

Have you thought of a USB version seeing that RS232 com ports seem to be disspearing off the modern PC's (especially laptops)?

Yes I had thought about it, but VB has it's own problems with the USB driver interface so if I were to do it I just use a cheap USB-serial adapter.

Did you have any thoughts on producing longer bar's/PCB for the read head to slide on? All the cheap Chinese calipers seem to come with a short 150 mm bar.

It would be nice to be able to make accurate scales of any length, but then would require some way of accurately calibrating them, which is probably the hardest part. Given that long scales (upto 1000mm) are available for not too much money (600mm are about £70), unless you need very long scales, is it worth making one???


Since there seems to be some interest here, I've attached the PC app and PIC files to this post. The VB app has a sort of demo mode that'll allow you to add scales and adjust the value by dragging the mouse over a button. The current version is a fixed 640x480 window to suit my panel-pc, but I have a part finished MDI (multiple document - so I could add hole layout and utility functions) version that I would like to finish ... sometime.