Posts for the month of March 2008

Digital Multimeter Software

Photo of multimeter

A couple of years ago, my father-in-law gave me a very nice multimeter; it has a serial port. Unfortunately, the software was Windows-only, and I don't have a machine running Windows. (Lots of Linux, one OS/X, no Windows.)

I found the data sheet for the interface (it is still available here), and then wrote a Python program to decipher it from a set of bits (indicating which LCD segments are lit) into something more human-readable.

Since others may find it useful, I am publishing it here under the GPLv2 (or later).

If your serial port is, say, /dev/ttyUSB0, you would run it something like su -c "./ /dev/ttyUSB0", and use ^C to kill it. The output will look something like this:

1206840186.138602 DC V AUTO RS232 - 009.8  m V
1206840186.419604 DC V AUTO RS232 - 007.8  m V
1206840186.669599 DC V AUTO RS232 - 007.8  m V
1206840186.918569 DC V AUTO RS232 - 008.3  m V
1206840187.168605 AC V AUTO RS232 ~ ---.-  m V
1206840187.449606 AC V AUTO RS232 ~ 304.8  m V
1206840187.761612 AC V AUTO RS232 ~ 300.8  m V
1206840188.010604 DC uA AUTO RS232 ---.- u A
1206840188.260576 DC uA AUTO RS232 000.0 u A
1206840188.541612 DC uA AUTO RS232 000.0 u A
1206840188.790602 DC uA AUTO RS232 000.0 u A
1206840189.040602 DC mA AUTO RS232 --.--  m A
1206840189.331640 DC mA AUTO RS232 00.00  m A
1206840189.601607 DC mA AUTO RS232 00.00  m A
1206840189.881570 DC mA AUTO RS232 00.00  m A
1206840190.132610 OHM AUTO RS232 ---.-  Ohm
1206840190.381606 OHM AUTO RS232 ---.-  Ohm
1206840190.631607 OHM AUTO RS232  .0F   K Ohm
1206840190.880600 OHM AUTO RS232  0.F   K Ohm
1206840191.130583 OHM AUTO RS232  0F.   K Ohm
1206840191.398708 OHM AUTO RS232  .0F   M Ohm
1206840191.660601 OHM AUTO RS232  .0F   M Ohm
1206840191.941613 CONT RS232 BEEP Open  
1206840192.191605 CONT RS232 BEEP Open  
1206840192.440545 CONT RS232 BEEP Open  
1206840192.690597 CONT RS232 BEEP Open  
1206840192.940560 CONT RS232 BEEP Open  
1206840193.189600 CONT RS232 BEEP Open  
1206840193.439560 HZ AUTO RS232 ---.-  Hz
1206840193.720864 HZ AUTO RS232 060.0  Hz
1206840193.969599 HZ AUTO RS232 060.0  Hz
1206840194.239601 HZ AUTO RS232 060.0  Hz
1206840194.500598 HZ AUTO RS232 060.0  Hz
1206840194.789571 HZ AUTO RS232 060.0  Hz
1206840195.061609 HZ AUTO RS232 060.0  Hz
1206840195.342567 HZ AUTO RS232 060.0  Hz
1206840199.105551 HFE RS232 0000 hFE 
1206840199.354549 HFE RS232 0000 hFE 
1206840199.666572 HFE RS232 0000 hFE 
1206840199.916550 HFE RS232 0000 hFE 

Update: This tool now has its own project page, DigitalMultimeter.

New Bit of the Internet

Long overdue, I am finally putting together my own little place on the internet where I can post code and thoughts I think worth talking about. I'm using Trac as the underlying engine for this little endeavor because I like it, and maybe a little because I'm biased.