LocoNet supports up to 4096 track sensors. Sensors are generally numbered on the basis of 256 sensor boards each of which can have 16 sensors: 256*16=4096. This convention comes from the BDL168 detector having 16 inputs, and having to be assigned a sensor board number when set up.
On the South Downs Railway we have sensor messages generated by DAC20, BDL168, DTM30 and SIGM20 devices. To keep a record, here is the list of sensor numbers in use:
| Board type | Board number | Sensor number(s) | Purpose |
| SIGM20 serial 65 | 20 | 1-8 | Track occupancy sensors, from BD4 |
| BDL168 | 21 | 1-16 | Track occupancy sensors |
| BDL168 | 22 | 1-16 | Track occupancy sensors |
| BDL168 | 23 | 1-16 | Track occupancy sensors |
| BDL168 | 24 | 1-16 | Track occupancy sensors |
| BDL168 | 25 | 1-16 | Track occupancy sensors |
| BDL168 | 26 | 1-16 | Track occupancy sensors |
| BDL168 | 27 | 1-16 | Track occupancy sensors |
| BDL168 | 28 | 1-16 | Track occupancy sensors |
| BDL168 | 29 | 1-16 | Track occupancy sensors in Portsmouth goods yard |
| BDL168 | 30 | 1-16 | Track occupancy sensors in Portsmouth goods yard |
| DAC20 serial 2 | 161 | 1 | microswitch on Eastleigh lift-up section. ON when flap in normal position. |
| DAC20 serial 2 | 161 | 2-5 | Track occupancy sensors, from BD4 |
| DAC20 serial 4 | 158 | 1-4 | Track occupancy sensors, from BD4 |
| DAC20 serial 684 | 159 | 1 | microswitch on Portsmouth lift-up section. ON when flap in normal position. |
| DTM30 | 160 | 1-4 | interlocks with DTM30 at Eastleigh |
| DTM30 | 160 | 5 | button press to signal traincontroller to start oil train schedule |
| DTM30 | 160 | 6 | A "toggle" button to signal traincontroller that track 1 is/isn't available |
| DTM30 | 160 | 8 | A "toggle" button to signal traincontroller that track 2 is/isn't available |
| DAC20 serial no. 6 | 162 | 1-4 | Track occupancy sensors, from BD4 |
| DTM30 ser 457 | 163 | 1-16 | DTM30 special functions triggered by button presses |
| DTM30 ser 457 | 164 | 1-4 | DTM30 interlocks |
| DTM30 ser 457 | 164 | 5-8 | DTM30 special functions triggered by button press |
| DTM30 clanfield | 165 | 1-4 | DTM30 interlocks |
| DTM30 clanfield | 165 | 5-7 & 9,10 |
special functions: platform 3-1 access & schedule requests |
| TXC1 | 240 | 1 | reports occupied while turntable is turning |