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WIKA operating instructions, model GDM-RC-100-T
EN
14499439.01 01/2022 EN/DE
5. Commissioning, operation
5.5 Modbus
®
The Modbus
®
communication protocol is based on a master/slave architecture. The
protocol implemented in the model GD-20 gas density sensor is Modbus
®
-RTU with serial
transmission via a 2-wire RS-485 interface.
The Modbus
®
protocol is a single-master protocol. This master controls the entire data
transfer and monitors any possible timeouts (no reply from the addressed instrument).
The connected instruments may only send messages after request by means of the
master.
Modbus
®
-RTU (RTU: Remote Terminal Unit) transmits the data in binary form, guaran-
teeing a good data throughput.
Detailed information on the protocol under www.Modbus.org
5.6 Modbus
®
start-up kit
The gas density sensor, with the optionally available start-up kit (order no. 14075896),
can be configured for operation at the measuring location.
A further function is an integrated data logger, showing measured data in a specific
cycle or writing it in a file.
The start-up kit consists of:
■
Power supply unit
■
Interface converter (RS-485 to USB)
■
USB cable type A to type B
■
Sensor cable with M12 x 1 connector
■
Adapter cable for models GDM-100-T and GDM-RC-100-T
■
Modbus
®
tool
5.6.1 Establish connection to the PC
RS-485
USB
+
-
Interface converter
Voltage supply