The communication between the instrument and the external device is RS485, using MODBUS protocol-RTU mode.
MODBUS is visit/response protocol, provides function code prescribed service. It used for host/guest communication between different type bus and network connection device. The host sends a command to visit the guest and the guest receives – processes the command then responds to the host.
MODBUS has 2 transmission modes, RTU or ASCII. Our instrument uses RTU.