This repository describes hardware and software required to support a RS-232 connection between the Sinometer UT60G Digital Multimeter and an Arduino UNO microcontroller.
The UT60G DMM is available from sources like Amazon.com for around $40.00. It is built around the Cyrustek ES51978 chip for which the data sheet appears to be correct in most but NOT ALL respects. However I believe all inaccuracies have been identified and corrected in the software provided here. A description of the 9-byte data packet used by the UT60G to tramsmit the current reading starts on page 10.
Three RS-232 connections between the UT60G and a microcontroller such as the Arduino UNO are required. (Rx, DTR, and Gnd). Additionally a means must be provided to translate between the TTL logic voltage levels of the microcontroller and RS-232 logic levels of the UT60G interface. A simple schematic of a suitable level conversion circuit for this using the popular MAX232 chip is provided as a pdf file in this repository.
Although the UT60G is capable of continually sending a new data packet related to the current meter reading out its RS-232 port about once per second, the DTR handshake line and related software provided here will only query the Digital Multimeter and receive a response data packet when requested by the Arduino sketch.
Note that due to the optical isolation provided by the UT60G RS-232 interface, NO electrical connection exists between the meter and the Arduino microcontroller.