Extech EX540 / Digitech QM1575 python reader

[Harvs]

For anyone who's used the software that comes with this meter, you'll understand it's not the pinnacle of functional software.

As part of my DMM Tablet project I've written a decoder to convert the serial stream from this DMM into something usable.  So feel free to use it to implement your own functionality 

http://www.electronicsinoz.info/extech-ex540-digitech-qm1575-python-decoder/

Any questions or bugs, please let me know.

[Wytnucls]

How bad is the Extech software? Do you have a capture of the computer interface?

[Harvs]

Sure, attached.

It's got a few bugs.  E.g. if the port which it remembers the device being on isn't available (e.g. windows has assigned a different port this time) it crashes and wont start.

But mostly, other than just capturing readings and exporting them to an excel file, it simply doesn't do anything.  In my opinion, the whole point of connecting your DMM to a PC is so you can do things like calculate currents across external shunts, or use multiple DMMs to do power calculations, or statistics, or single captures of resistances etc.

[Wytnucls]

It is very similar to the Uni-T software. Very basic indeed. I can run 2 meters in their own windows simultaneously, but still have to import all the data into a spreadsheet for any kind of manipulation. Clock sync is also a problem, with rapidly changing values.

[Harvs]

It is very similar to the Uni-T software. Very basic indeed.

Surprisingly similar isn't it.

I can run 2 meters in their own windows simultaneously, but still have to import all the data into a spreadsheet for any kind of manipulation.

I'm not sure (I don't have two Extech's,) but I'm dubious as to whether you can actually have muliple EX540's linked at the same time.  The RF link looks like one of the simple 433MHz on/off keying tx/rx sets you get for $5.  I have my doubts about there being in ability to have them both occupy the same freq range at the same time.

Clock sync is also a problem, with rapidly changing values.

Yes, but I think this is always a problem with instruments that don't have a clock sync input.  Even in the screen grab I took the sample time varies between 1-4 seconds, which it clearly doesn't, it's just when the PC put a timestamp on the sample.

[Harvs]

Now with added Bluetooth:
http://www.electronicsinoz.info/extech-ex540-digitech-qm1575-adding-bluetooth/