Review on Tekpower TP4000ZC Auto Ranging DMM with USB Interface - PC Based Digital Multimeter, Similar to MS8220R, Computer Compatible by Todd Foster

I bought this meter purely because of the inexpensive RS-232 support. I needed to log the voltage for a project in two days and this was the easiest way to do it. Good news? The RS-232 works as advertised and the AA batteries were enough to run my tests. COM port settings: 2400, 8-N-1. The only bad news is that the log this meter outputs is not "human readable" but rather the encoding of the actual display segments that are on or off. Fortunately, some rudimentary software is included that will probably work for most people. Instead I used the Linux program QtDMM which supports a number of RS-232 capable gauges including this one after finding and specifying the correct 14 byte protocol in the setup menu. Otherwise it's just a simple automatic range finder, an adequate bot, not exceptional.