WIKA GDM-RC-100-T Betriebsanleitung Seite 23

5. Commissioning, operation
5.5 Modbus
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The Modbus communication protocol is based on a master/slave architecture. The
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protocol implemented in the model GD-20 gas density sensor is Modbus
transmission via a 2-wire RS-485 interface.
The Modbus protocol is a single-master protocol. This master controls the entire data
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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-
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teeing a good data throughput.
Detailed information on the protocol under www.Modbus.org
5.6 Modbus start-up kit
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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
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Interface converter (RS-485 to USB)
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USB cable type A to type B
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Sensor cable with M12 x 1 connector
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Adapter cable for models GDM-100-T and GDM-RC-100-T
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Modbus tool
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5.6.1 Establish connection to the PC
Interface converter
RS-485 USB
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WIKA operating instructions, model GDM-RC-100-T
Voltage supply
-RTU with serial
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EN
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