A Navtech radar with the SafeGuard functionality enabled can act as a Modbus master or a 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.
The key aspects of the radar’s Modbus configuration are shown in the screenshot of the radar’s web user interface below. These settings apply, irrespective of whether the SafeGuard functionality is enabled in the radar.
from this page, the following settings are available:
Modbus Mode: This is the data output mode.
None: Disabled
Master: The radar will pole other devices that are operating as a slave.
Slave: The radar acts as a server and makes alarm data available to the Modbus master.
Modbus Address: This is the IP Address of the slave and is only available to be used if the radar is acting as a Master. In slave mode, the address is the same as the radar.
Port: This is the port used by Modbus in order to connect to the slave.
Health Offset: This is the register offset used by Modbus. If this value is set to 0, the radar’s health data will be presented in the lowest numbered Modbus holding registers.
The six SafeGuard alarm states are presented by the value in a specific Modbus holding register. This register can be configured through the radar’s web user interface as shown below:
Note that this functionality is only supported in radars with firmware v3.0.0.92 or later.
The screenshot of a very simple ModBus listener, below, shows how the radar health is presented in the lowest registers
