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Tower Controller Review

by Don Fiehmann

Buy Tower Controller Here

Don Fiehmann gives us a brief look at this flexible Digitrax LocoNet™ tool.

The computer and the layout room

The computer has become more a part of model railroading. With the available of older computer systems cost is no longer a big problem. In many cases computers that are only a few years old, are still very usable and finding there way into the layout room. Programs designed to control layout functions have become more sophisticated. It is possible to have a computer run trains, set turnouts and even simulate a prototype CTC (Centralized Traffic Control) panel. Programs like Decoder Pro and Panel Pro that are free over the Internet have help with the marriage of the computer and the layout.

Basically the computer “talks” to the command station or layout over some type of interface. With Digitrax the interface is the LocoNet. LocoNet is a peer to peer network, a bit like the Ethernet. Each device on the LocoNet is independent. Each device has its own address. The computer can communicate with switch machines and locomotives by sending out commands. There are also devices that allow the computer to read back the status of switches and block occupancy. Most of these devices are limited to just one type of function. This can be a limiting factor to the automation of a layout.

The Tower

TC-64 Tower Controller is designed to overcome many of these limitations by having programmable I/O (Input and Output) ports. The Tower has 64 I/O lines that can be programmed as either an input or an output. The I/O lines are in groups of 8, and there are 8 connectors on the Tower. Each of the of the 8 connectors for the ports are 10 pins connectors that use standard flat ribbon cable. The drawing below shows the how some of the devices can be wired to the Tower. Switch machines, signals, block sensors are all possible. Most devices on the layout require some type of adapter to either supply the right voltage level to an input or have the power to drive an output device.

Programming is needed to determine if a line is an input or an output. Each line has an output of up to 15mA and has a 4.7K pull up resistor. Each port of 8 can be assigned as either an input or and output, but not mixed on a single port. The Tower requires a power input of 9 to 16 volts AC or DC at 0.5 amps.

The Tower comes with power connector, 8 ribbon cable connectors and a LocoNet cable.

LED indicators, power input and LocoNet
connectors are all located on the end of the Tower.

Tower Inputs

The inputs are assigned as 8 to a port. Each port can be either an input or an output, but not mixed. Inputs can be programmed to send a signal on a positive, negative or either transition of the input. The signals can be programmed to be sent to addresses on the LocoNet. Inputs like block occupancy require a block detector plug-in card that provides the circuits to sense the block, then drives a line to the Tower. Simple switch contacts can be wired directly to the Tower inputs.

The BOD-8 Block Occupancy detector uses a current transformer to sense block occupancy. The CT-Coil-Set (set of 8) current transformers are connected with a two-wire connection. The BOD-8 can be either mounted on the Tower or located some where else on the layout. The 10 wire ribbon cable can be used to allow the BOD-8 to be mounted in a remote location from the Tower.

Tower Outputs

There are daughter boards available for driving outputs from the Tower.

The 4ASD is a card that is designed to operate signals. (4 Aspect Signal Driver) This board is specifically designed to drive simply wired 3-4 aspect position signals utilizing 3 yellow LEDs in series for each position by providing 9V to the internal dropping resistors. Multiplexed outputs allow for direct drive of four 3 or 4 aspect signal heads mounted along a single 10 wire cable. No extra hardware is required at each signal head. The 4ASD has a Tower Controller standard ribbon connector interface.

The DCDB-8 is designed to operate motor drive switch machines, like the Tortoise™. This card uses power supplied by an external source. Outputs are rated at 1/4 amp continuous and 1 amp momentary. The card uses an “H” bridge driver. There are 8 independent drivers on the DCDB-8. Screw terminals are used for connections to the board.

The SCSD-8 is a Single Coil Solenoid Driver. This 8 line, optically isolated, single ended, high current, high voltage DC driver can drive up to 1A per line at up to 30VDC. (PTC fuse limited to 2-3A total per board for safety) The SCDB-8 has a Tower Controller standard ribbon connector interface. This board can be used to drive solenoids that use up to 1 amp. It can also be used to drive other items like lamps.

More information

The manual for the Tower can be downloaded from the RR-CirKits website ( Many of the photos and the diagram in this review are from this website.

Panel for setting up the ports on the Tower

Programming the Tower

In order for the Tower to operate it must be programmed to match the layout requirements. This can be somewhat complex. But, the programming can be greatly simplified by using the JMRI (Java Model Railroad Interface) Decoder Pro. The profile for the Tower is in the latest beta release( 1.7.5) of Decoder Pro. There are two views, one setting up the functions of the 8 ports and then 8 separate views for programming each of the 8 ports.

This is the panel for setting up each of the 8 ports.

Testing The Tower

I needed to find a good test case for The Tower. Dave Parks is in the process of installing a phone system on this large home layout. He has 21 phones installed in various locations around the layout. Dave rejected using wireless walkie-talkies because they were not prototype for his era. The Tower is to be used to call each phone with blinking lights instead of a ringing phone. Ringing phones in a layout room could become a big distraction. The output of the Tower is only 15mA and the lamps in the phones require near 40mA. The SCSD-8 Single Coil Solenoid Driver interface card is needed to drive the lamps from the output of the Tower.

Dave’s application shows the flexibility of the Tower. Other clubs are looking at automating layout control using the Tower as sort of a central office for the layout.

We welcome comments or suggestions from readers; please write or call.

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