Over the weekend my trusty old multimeter gave up the ghost (it must be 15 years old so I can’t complain really). A quick hunt around the local area revealed nothing of great interest so a lunchtime trip to Maplins was sorted. A short while later and I’m the owner of a “True RMS Autoranging Multimeter with USB PC Interface”.
Just had a quick play – seems quite nice for the price (although the label instore did suggest that 30 quid was half price clearance). Fairly fully featured, including Tranny testing for Foo (I’m sure there are websites about that) and Capacitor measurements along with a temp probe. Backlit as well which I hadn’t realised. All in all, quite nice. The software provided however is windows only.
A little bit of playing and I’ve got it working nicely on the Mac. First, download the serial-usb widget driver from http://www.silabs.com/. Install and reboot (yes, a reboot really does seem to be needed).
Once it’s back, download and install qtdmm – I used version 0.8.12 which seems fine.
Then into the cofiguration page and set Digitech QM1537 as the meter and then select the usb port from the drop down list. This might be different on your machine (I had two listed for some reason – the first worked fine).
That should be it! Make sure the meter is in USB mode (hold the USB button until it switches) and it should all work. If it doesn’t work at all, check you have the correct USB-serial port – try the other one 🙂
If you have readings on screen that don’t appear to agree with the meter than double check you have the correct settings for the meter – I originally tried to set it all up by hand and although it was talking, it appeared to display random numbers! Also, it seems that maximum sample rate is one a second (turning it up in qtdmm appeared to make no difference). I’ve not tried sniffing at the actually serial port to see what it sends but I suspect it’s not rocket science. Job for another day I feel 🙂
Hope this helps someone