Serial port communication test instrument

The utility model relates to a serial port communication test instrument, which can test a serial port in the common intellectualized applied system as an isolated soft hardware entity. The structure comprises a master control module, a communication module, a keyboard module and a display module. The test instrument is designed with an RS485 bus, an RS232 bus and a Modem bus. Only simple connection is needed, according to actual conditions, to test communication in various sites. The Modem data transmission interface is provided to adjust and teat the Modem far-end system, which can simplify the adjusting and test equipment on site. Single-chip microcomputer technique is adopted with high anti-interference capability; wiring and maintenance are convenient, flexibility and extension are strong, and a compound key mode is used, which is easy to control.