Modbus/TCP registers for O3 sensor

Two O3 gas sensors are connected to Sensor1 and Sensor2 port of a Base Wired Gateway.
What is the Modbus/TCP register to read value of the O3 gas sensor at Sensor1 port of the Gateway?
What for the sensor at Sensor2 port?

As I know, based on their modbus manuals, node 0 and node 1 are reserved for internal temp and ping.
node 3 etc.. will be the start of the sensor nodes.
If your sensor only has 1 node so probably it will fall between node 3 and 4
wherein node 3 = port 1 and node 4 = is port 2.
but please verify this first as I do not have those sensors