The transmitter and the connected probes are treated as separate Modbus devices, each with their own fixed unit identifier (unit ID) value. The unit ID in the Modbus request defines the intended recipient of the request.
| Device | Unit ID |
|---|---|
| Transmitter with barometer module | 240 |
| Measurement device connected to probe 1 connection terminal | 241 |
| Measurement device to probe 2 connection terminal | 242 |
The unit IDs of the connected measurement devices identify the measurement devices based on the probe connection terminal that they are connected to. The measurement devices use these unit IDs (241 and 242) only when they are connected to the transmitter. When the measurement devices are accessed directly without the transmitter, the measurement devices have their own Modbus address settings instead of these unit IDs.
If the measurement device fails to respond to the request, the transmitter responds to the client with the exception code Gateway Target Device Failed to Respond.
| For probe-specific register information, see the connected probe's Modbus documentation. |