IRDOT-3 & 3D
Both the IRDOT-3 and IRDOT-3D have a built in double pole relay and the facility to also operate both detect and undetect LED's or a bicolour LED.The IRDOT-3D has in addition, the following selectable delays, 3, 6, 9, 12, 15, 18, 21, and 24 seconds.These are selectable by connection to the terminal block.
Operation
When the IRDOT-3D detects a train, it lights a red LED and operates a double pole relay.The IRDOT is supplied with a 5mm diameter red LED connected to the correct screw terminals.This provides an aid while installing the IRDOT to check for reflections off obstructions.After installation the LED is wired to the control panel.The double pole relay is effectively the same as two single pole double throw "changeover" switches.
The diagram below shows how the relay contacts correspond to the terminals on the board.
LED Wiring
The IRDOT3 is supplied with the red "detect" LED fitted with the long leg to "l" and short leg to "k".This LED will light when a train is detected.A second LED may be fitted long leg to "k" and short leg to "l".This will light when not detecting. If a number of IRDOT3s are used, each with a single LED, these can be wired with long leg to "l" and short leg to "0V".The advantage to this is that "0V" is a common connection thus nearly halving the number of wires needed.
The two diagrams below show how to wire up both 2 leg and 3 leg bi-colour LEDs.
Setting delay times
As supplied, the unit has a 3 second delay, i.e. it detects a train immediately but remains detected for 3 seconds after the train has left.By connecting wires between the "g", "h", and "i" terminals, longer delays are obtained.Refer to the table and diagram below.
| Delay "secs" |
Terminals | |||||
| g | h | i | ||||
| 3 | - | - | - | |||
| 6 | - | - | X | |||
| 9 | - | X | - | |||
| 12 | - | X | X | |||
| 15 | X | - | - | |||
| 18 | X | - | X | |||
| 21 | X | X | - | |||
| 24 | X | X | X | |||
