A Navtech radar with the SafeGuard functionality enabled can act as a Modbus master or a modbus Modbus slave device.
In addition to a single register that presents the alarm state of the six SafeGuard detection & reporting zones, there are further registers which allow a connected device to report various aspects of its' health.
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The screenshot of a very simple ModBus Modbus listener, below, shows how the radar health is presented in the lowest registers
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, and how the six alarm states are presented.
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The watchdog counter is an incrementing number - attached devices can monitor the change in this to identify that the Modbus communication link is correct and operational
Radar Health is presented as nine bits. The first three bits represent a “not-OK” status relating to the radar’s temperature, rotation speed and its' data output rate. The next batch of three bits represent a “warning” condition against each of the same three categories, and the final three bits represent an “OK” condition for each of the three health categories - as is shown in the image above.
The next three registers, as shown in the screenshot above, present the radar’s operating temperature (in DegC), its' rotation rate in mHz, and a value of Packet Rate, which is the number of azimuths of data presented per second.