Introduction

One of the functions often desired for a layout that has a CTC panel is some simple way to lock and unlock local turnout controls from the CTC panel. The most direct way to accomplish this is to enable/disable the 'Common' side of the switch providing local control.

Background

Prototype CTC panels often had the capability to lock and unlock the remote turnout mechanisms in order to allow local crews to change switch positions manually without constantly calling in to the dispatcher for changes in routing. There are various ways that modelers have chosen to simulate that function, including the issue of 'keys' to operators.

How It Works

The TC-64 uses different ports for inputs and outputs. These ports may be configured to send and respond to the same commands. I.e. an input port may generate turnout commands in response to contact closures. A second port may be addressed the same and respond to those commands by driving a turnout motor. TC-64 inputs require a contact closure to ground. If we use an output of the TC-64 to provide that 'ground' to the local contact we can enable or disable it remotely from the CTC panel.

Problems

The primary difficulty with this solution is to get the panel images correct to represent the 'lock' lever and indicators.

Advantages

The advantage of using the TC-64 for this operation is that it always sends the 'local' turnout commands on the LocoNet so that the CTC panel always shows the current position of the turnout, even without the extra expense of feedback contacts. Using a push button switch allows the use of multiple buttons at different locations. If the operator can not see the turnout position, and no use is made of turnout position indicators, then dual push buttons or a SPDT switch may be used.

The LED lamp is a visual aid to the local operator to show him when he has local control of his turnout.

The Wiring

Set the output (control) port to Type 'Driver'. Set the input (command) port to be 'Alt Button'.

Connect the LED indicators and local control buttons as shown below. Each button press of S1 will send alternate 'Thrown' and 'Closed' commands from the Input line at 1-2-10 as long as the Output line at 1-1-10 is low. If the Output line at 1-1-10 is high, then there will be no commands sent on button is presses.

Modifications

One modification is to use a SPDT local control toggle switch instead of a single push button. To do this wire the NC side of a double throw switch to the next input line so the SPDT switches are wired to pairs of inputs. The Input port configuration must be changed to be the custom setup as shown below. Note especially: Direction, Toggle, and Mode, for the port. Also Input Polarity, I/O Mode, and Input Control, for each individual line. (click to enlarge image)

The Parts

LED1 Indicator LED

R1 330 ohm

S1 button switch