The Modbus to SDI Protocol Converter (sometimes referred to as ‘BabelStar’) converts Modbus data to/from SDI-12 data. Alternatively it can convert High Speed Serial data to Modbus data.
SDI-12 is a standard protocol that defines exactly how a sensor must communicate with a datalogger. HSIO is a Unidata proprietary protocol.
In the Modbus to SDI-12 conversion the protocol converter acts as a Modbus slave on a Modbus Remote Terminal Unit (RTU) bus.
On receipt of a Modbus command from the RTU, the 6543 converts it to SDI-12. The SDI-12 command is sent to the SDI device, executed and the SDI response is converted to Modbus protocol and sent to the Modbus RTU. The data returned is selectable, as either BCD or floating point.