Just had a quick look at the serial output of the meter. It is actually very well isolated, and so this meter is a cheap way of data logging.
It appears the Semico CS7721CN chip is outputting data at 2400 baud in packages of 12 to 16 bytes - I haven't put a logic analyser on it yet. The sample rate period is about 700 ms.
I haven't found any data yet for the 7721 chip, so if anyone can find it, it would help.
I am expecting a format such as a range byte, 4 digits for the measures value, a function byte (volts, mA, uA, Capacitance, etc), a status byte (things like low battery), and some option bytes which include things like a bit for AC or DC mode. It appears the string ends with a linefeed byte (0x0A).
I have had a look at the sigrok.org site and it doesn't appear they support any CS7721CN based multimeters yet, but unfortunately half the contributors didn't bother to mention the multimeter chipset.
Richard.