SARAD GmbH
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Manual_Smart-Radon-Sensor_EN_12-03-2020.docx
Communication interfaces
For a communication between the Smart Radon Sensor and the data acquisition system two digital
interferences are provided. The RS-485 standard serial interference allows user to integrate the
instrument within corresponding network. The USB interface provides a quick way for sensors
configuration and maintenance. Once the USB cable is attached to the device, the RS-485 interface
will be automatically disabled. In such a situation only USB communication is possible. After
removing the USB cable the RS-485 interface will be reactivated.
RS-485
General
The communication over RS-485 interface can be realized with usage of two protocols: proprietary
SARAD protocol or industrial standard MODBUS RTU. The MODBUS protocol supports only the
transmission of the recent readings. For all other functions the SARAD standard protocol has to be
used. The protocol frames are explained in detail by the document “SARAD_MODBUS_Protocol”. The
complete MODBUS Documentation can be found in the internet under “modbus.org”.
Selection of the transfer protocol, addressing
To identify an instrument within a network, a unique address in the range of 1…250 must be
assigned. This address and the bus speed for MODBUS protocol can be programmed into the
instrument using the initialization software „Init_RadonScout”.
Important: The edit field „Address” contains, after loading the configuration parameters with „GET”
button, the current instrument address. Now, the desired address can be entered and transferred to
the instrument with „SET” button. The drop-down list labeled „Baudrate[bps]” contains two entries:
„9600” and „19200”. Those are used to select MODBUS protocol speed.
Please note that the parameters have to be read at first before uploading a new setting. Otherwise
the existing parameters will be permanently overwritten.