PPI4-K KATO Model Railway Points Position Indicator - 8 Points

About the Product

The BLOCKsignalling PPI4-K is a KATO model railway points position indicator that monitors up to 8 sets of polarity-reversing points and displays their last operated position using LEDs on a control panel or route mimic.

Designed specifically for point systems where the motor direction is changed by reversing the polarity of the supply, the PPI4-K monitors each switching operation and automatically updates the corresponding red or green panel LED. This makes it particularly suitable for KATO 2-wire points.

The module provides 16 monitoring inputs for up to 8 sets of points. Each detected change is automatically stored in memory, so when power is switched off and restored, the panel LEDs return to their previously recorded states.

Key Features

• Designed for KATO and other suitable polarity-reversing point systems.
• Monitors up to 8 sets of points.
• Provides 16 points-monitoring inputs.
• Displays the last operated point position using control-panel LEDs.
• Automatically remembers point positions when power is switched off.
• Adjustable LED brightness.
• Opto-isolated points-monitoring inputs.
• Suitable for control panels and model railway route mimic boards.
• Supports separate red and green indication LEDs.
• Compatible with suitable common-anode dual-colour LEDs.
• Can automatically control compatible 2-aspect signal LEDs from point operation.
• Supports both DC and suitable AC KATO point-control arrangements.
• Optional programming with no programming required for normal operation.
• Built-in LED lamp test function.
• Requires a regulated 12V DC power supply.
  

KATO Points Position Indication

The PPI4-K monitors the polarity of the voltage across each pair of inputs. The polarity indicates which direction the associated point has most recently been operated.

For example, if I1 is more positive than I2, one indication LED is illuminated. Reversing the polarity so that I2 is more positive than I1 switches the indication to the other LED. Only the most recently selected position remains indicated.

DC KATO Points Wiring

When KATO points are operated from a DC supply, a double-pole (ON)-OFF-(ON) spring-return switch can be used to reverse the polarity supplied to the point motor.

The PPI4-K monitors this polarity change and uses it to determine which panel indication should be displayed.

AC KATO Points Wiring

The PPI4-K can also be used where KATO points are operated from an AC supply using diodes to separate the positive and negative halves of the AC waveform.

In this arrangement, the point switch selects the positive or negative cycle relative to the common supply connection, allowing the PPI4-K to determine the selected point direction. The manual specifies 1N4001 diodes for this arrangement.

Automatic Position Memory

Every time the PPI4-K detects a change in point position, the new state is automatically stored in memory.

When power is switched off and subsequently restored, the LED outputs automatically return to their last recorded positions, so the control panel retains the previous route indications.

Control Panel LED Indication

Red and green LEDs can be fitted to a model railway control panel or route mimic to provide a clear visual indication of the last operated position of each set of points.

Each LED must be fitted with a 1kΩ series resistor and connected with the correct polarity. Reversing an LED can cause it to illuminate very brightly and fail, and may also damage the PPI4-K.

Suitable common-anode three-leg dual-colour LEDs can also be used.

2-Aspect Signal Control

The PPI4-K can also automatically operate suitable 2-aspect model railway signals according to the selected point route.

A red and green LED can be wired so that the signals indicate which route through the points is clear. For this application, the individual anode and cathode connections of the signal LEDs must be accessible; signal heads with a shared common anode or cathode are not suitable for this particular arrangement.

Important Wiring Information

High-current point-motor wiring can interfere with the low-power wiring used for the indication LEDs.

When constructing a control panel, the manual recommends keeping the high-power point-switch wiring separate from the low-power LED wiring, both within the control panel and between the panel and PPI4-K.

Electrical Requirements

• Power supply: Regulated 12V DC.
• Current consumption: Less than 25mA with all 16 LEDs illuminated.
• Points input voltage: 5V typical minimum.
• Maximum points input voltage: 25V DC / 24V AC half-wave.
• Typical points input current: 1mA with 12V input.
• Points capacity: Up to 8 sets of points.
• Number of monitoring inputs: 16.
• LED series resistor: 1kΩ per LED.
• Dimensions: 50mm × 100mm.

These figures are from the specification section of the manual.

The PPI4-K should be powered from a regulated 12V DC supply. The manual recommends a supply rated between 0.25A and 1A and warns against using unsuitable accessory outputs from train controllers because they may not provide sufficiently smooth or stable power.

A compatible regulated power supply is available separately: PSU2 12V DC 1A Model Railway Power Supply

Documentation & Support

For detailed information on installation, wiring connections, and troubleshooting, please download the latest instruction manual:

Product Instruction Manual