Controlling Switches with the ASC

The Accessory Switch Decoder (ASC) can be used for many different types of accessories and switches. The ASC will operate both twin-coil and motorized switch machines, even DC motors.

While you can use your ASC to control your switches regardless of whether they are powered by the track or by a constant accessory voltage, we highly recommend converting your switches to constant voltage when using command control. Not only will your switches operate more reliably, at a sustained 18 Volts, the switch lamps may generate enough heat to melt the plastic lanterns.

Wiring the Back End

The connections to from the ASC to your power supply and command station are the same no matter what you attach to it. For more complete instructions on this, see this page.

Wiring the Switch Machines


This ASC is wired for power and has a jumper between the COMM posts on the business end. All that remains is to attach the Through and Open leads. The Programming Jumper is at left.

First, attach a connection from the AC Ground of your accessory transformer to the “COMM” port on the ASC. If all four switch locations will be used and all operate off of ground, then you can add a jumper from one COMM to the other.

Next, attach the AC Hot input lead from your switch motor to the AC Hot (14V constant) bus from your accessory transformer.

Attach the two output wires, Through or Out to the two ports on the ASC for that switch. For FasTrack remote switches (not already prepped for Command Control), simply remove the wire connections from the remote control on the underside of the base.  For FasTrack switches, you’ll want to run a third wire from the Ground position on the underside to the COMM port on the ASC. On machines from other manufacturers, these wires may not be labeled as such. Simply guess which is Through and Out. You can’t do any harm to the machine, it will just throw opposite the you would like if the wires are reversed. If you are wrong (if you have a 50/50 shot you’ll probably be wrong about 90% of the time!) simply switch the wires at the screw terminals on the ASC.

For Tortoise and other DC Switch Machines


The Tortoise machine mounts beneath the platform and can be used on many gauges and brands of track. The outer two terminals are used for power. The inner six connect to a pair of very useful relays.

For any switch machines operating as DC motors, you need to add one additional step. To operate the DC motor on AC, you must first install a pair of 1 Amp diodes on one lead (either DC+ or DC-). These diodes are inexpensive and can be found at Radio Shack or other electronics stores and wholesalers. If you have a lot of switches to convert, it may pay to order in bulk from a larger wholesaler like DigiKey or Mouser. Wire the two diodes so that their cathodes (the silver banded end of the diode) are at opposite poles. See the diagram at right.

Install one diode into the “O” position and the other into the “T” position for one of the four switches on the ASC.

Connect the other DC lead on the switch machine to the AC Hot (14V) bus from your accessory power supply. This completes the circuit.

If the switch does not throw in the direction you want, (it goes to the Throw position when you want Open, etc.), simply reverse the two diode leads on the ASC.


To program the ASC, like all of these controllers, you must remove the programming plug on the side of the module. Do not lose these plugs! With the plug off, the controller is in program mode. Also, only one device can be programmed at a time. Once programming is complete, replace the plugs to get back into Operations mode.

To operate slow motion machines like the tortoise, you need to program the ASC for constant voltage. Twin coil machines use only a momentary contact. First we need to program the voltage. Remove the program plug and use your TMCC or LEGACY remote to do the following:


With the program plug removed, your ASC is programmed with the press of a few buttons.

  1. Press Switch
  2. Press 99 for Constant Voltage or 98 for Momentary
  3. Press Set
  4. The Green LED on the ASC should light when you press Set to confirm that it is now programmed for constant or momentary voltage.

Next you need to program the address. The ASC can handle up to four switches. To program the ASC for addresses 1-4, use address 1. You only need to do this once, not four times. For the next ASC, you would assign address 5 and so on. Note that the ASC is set so that if you would program the next ASC as switch 6, 7 or 8, it will still assign numbers 5-8 for that ASC, so you can’t leave any holes by mistake. LEGACY will allow up to 99 switch addresses.

So, again with the program jumper removed, do the following with your remote to program the address:

  1. Press Switch
  2. Press 1  (or the appropriate number for subsequent ASC’s)
  3. Press Set
  4. The Green LED on the ASC should light when you press Set to confirm that it is now programmed for Address 1-4 (5-8, etc.)

Simply replace the programming plug when you have completed these steps. Your programming is complete! Your switches are ready to go.

Operating Your Switch

Now that you’ve wired and programmed your switch, it’s time to give it a test. Let’s assume you’ve wired this switch into position number 3 on your ASC. Using your remote, press:

  1. Switch
  2. 3
  3. AUX 2 (Through)
  4. AUX 1 (Out)

The switch should move back and forth as you press the Through and Out buttons.

To see all of this worked out step by step on video with a Tortoise, DZ1000 and FasTrack switch, just watch this video to review. [youtube=]

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