IRP2-NS Infra-Red Model Railway Points Controller with Automatic Train Routing

About the Product

The BLOCKsignalling IRP2-NS is a compact infra-red model railway points controller with automatic train detection, designed to automatically operate and route trains through 3-wire point motors. Its built-in infra-red sensor detects passing trains directly from beneath the track, allowing points to be changed automatically without requiring a separate train detector.

The IRP2-NS can route trains in a predictable or random sequence, allowing selected trains to be automatically sent onto a branch line. It can also measure how long a train passes over the sensor, allowing short and long trains to be routed differently.

For example, the controller could automatically send most trains along the main line while periodically routing a train onto a branch, or route a long express train differently from a shorter locomotive or shunter.

The controller is highly programmable, with adjustable routing ratios, sensor sensitivity, operating delays, point-motor drive duration and automatic point resetting. This makes it suitable for a wide range of automatic model railway routing applications.

Key Features

• Built-in infra-red sensor for automatic train detection.
• Automatically operates model railway points when a train is detected.
• Compatible with standard 3-wire twin-coil solenoid point motors.
• Also supports suitable 3-wire slow-acting motorised point motors.
• Predictable or random automatic train routing.
• Adjustable proportion of trains routed to a branch line.
• Can distinguish between short and long trains using detection time.
• Train-length threshold can be programmed to suit the layout.
• Suitable for facing and trailing point applications.
• Automatic timed return of points to their original position.
• Adjustable delay before points operate.
• Adjustable point-motor drive duration.
• Adjustable infra-red sensor sensitivity.
• Can retain the last point position when powered down.
• Optional manual control-panel switches can be used alongside automatic operation.
• Suitable for reversing-loop and terminus routing applications.
• Compact design with the sensor built directly into the module.
• Fully programmable using the on-board push button.
  

Infra-Red Train Detection

The IRP2-NS is normally installed beneath the track, with its built-in sensor looking upwards through an 8mm hole in the baseboard. The infra-red components are approximately 2.2mm in diameter, allowing them to see between the sleepers even on smaller-scale track.

At normal sensitivity, the sensor has a detection range of up to approximately 25mm. Its sensitivity can also be adjusted to suit different rolling stock, mounting positions and lighting conditions.

Points Motor Wiring

For conventional 3-wire solenoid point motors, the IRP2-NS is used with a Capacitor Discharge Unit (CDU). The CDU provides the high-current pulse required to operate the point motor, while the IRP2-NS determines when and in which direction the points should operate. One CDU can be shared between multiple points-control modules.

The IRP2-NS can also operate suitable 3-wire slow-acting motorised points, such as geared DC point motors. The output duration can be increased to allow these motors sufficient time to complete their movement.

Automatic Train Routing

With facing points, the IRP2-NS can automatically decide whether an approaching train continues along the main line or is diverted onto a branch.

Routing can be predictable - for example, every fourth train - or random, with the proportion of trains sent to the branch adjustable to suit the layout.

Route Trains by Length

The IRP2-NS can also measure how long the train obstructs the sensor and use this to distinguish between short and long trains.

For example, longer trains could automatically be sent to one route while shorter trains are directed to another. The train-length threshold is programmable rather than being fixed; the manual specifies a programmable detection period and a default of five seconds.

Automatic Points Reset

The points can remain in their new position after a train passes or be programmed to automatically return to their original position after a selected delay.

This is particularly useful for trailing points and other layouts where the points should temporarily align with an approaching train before returning to their normal route. The reset delay can be programmed from 2 to 240 seconds, or disabled.

Other Layout Applications

The IRP2-NS can be configured for more advanced layouts, including DCC reversing loops and terminus/stub-end stations. For example, it can change points each time a train passes to alternate the route through a reversing loop, or automatically select arrival and departure tracks at a terminus.

These applications may require additional equipment such as a suitable DCC autoreverser or shuttle controller.

Electrical Requirements

• Normal power supply: 12V DC.
• Current consumption: Approximately 50mA.
• Recommended power supply rating: 0.25A–1A.
• Train detection: Built-in infra-red reflection sensor.
• Typical detection range: Up to approximately 25mm.
• Sensor mounting hole: 8mm.
• Sensor sensitivity: Adjustable from 1–10.
• Solenoid points: Standard 3-wire twin-coil motors.
• Solenoid point operation: Requires a suitable CDU.
• Slow-acting points: Compatible with suitable 3-wire motorised point mechanisms.

For normal 12V DC operation, use a regulated power supply. The manual specifically warns against using the auxiliary output of a train controller because these outputs may be insufficiently smooth or stable.

Documentation & Support

For full installation instructions, wiring diagrams, operating modes, programming options and troubleshooting, please refer to the latest instruction manual:

Product Instruction Manual