POINTS POSITION INDICATOR PPI4
Advanced PPI with Adjustable Brightness & Simplified Wiring
Monitors the brief positive operating voltage across points motors when they are switched
Lights a corresponding led on a control panel to show the last operation of each set of points
Saves all settings automatically to memory when the power is switched off
Monitors up to 8 sets of points
Opto-isolated inputs accept voltages from +5V to +60V
The Points Position Indicator (PPI) monitors the brief switching voltage to either of the two
coils of a points motor, and displays the last operation using coloured leds which can be
mounted on a route mimic.
Manual methods to switch points include simple spring-loaded switches, push buttons, probe
and stud, etc and the points coils have a common connection to the ground of the supply.
When points are driven from DCC Accessory decoders, the decoders most often provide a
+12V supply to the common of the points coil, and then switch the other connections of the
coils to ground to switch the points (use PPI2-DCC with these).