The utility model discloses a communication system for measuring device is synthesized to transformer, including RS485 bus, host computer, host computer, at least one from machine, all wire changing device, an at least RS485 expander 600 and an at least intelligent Mobile Terminal at least, through the host computer transfer will host computer, a plurality of RS232 communication interface's measurement subset, outside intelligent Mobile Terminal, extension RS485 bus and a plurality of wire changing device of cutting organically link together, also rationally integrate various interface mode effectively together simultaneously, and it is more simple to work a telephone switchboard, and the communication is reliable, can resist all kinds of interference of forceful electric power, and easilyextension.