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Step 2: Functional Zones

To determine Power Requirements, you looked at your plan and did a rough approximation of the boards and peripherals you will need. Now you are going to refine your initial estimates by dividing the layout into functional zones, then assessing what resources will be needed in each zone.

Zone Criteria #

Layout control zones are determined using multiple criteria. The intent is to create a network of load-balanced zones that work well together.

Physical Area #

The standard “envelope” for an LDG Layout Control Node is 16 square feet.

In practical terms, that ranges from a 4′ x 4′ peninsula or table layout, to an 8 ‘ x 12″ shelf layout section. Its a fairly flexible rule-of-thumb providing a baseline for LCN distribution. Additional factors may increase or decrease the number of LCN’s needed.

Blocks #

An LCOS Layout Control Node can monitor up to 8 blocks using the LCBD4 LCOS Client Node Block Detection Kit plus two additional DNCT2B Block Feeder/Sensor modules. The block feeder/sensor system has a longer reach than other components. Feeder/sensor boards (DNCT2B) can be as far as 7′ from the sensor interface, giving the block feeder/sensor system a 14′ maximum reach. This reach is useful with shelf-style around-the-room layouts that have long stretches of mainline without other track objects, and gives you a lot of flexibility in assigning block monitoring roles to your LCNs.

Turnouts #

An LCOS Client can manage up to 8 local turnouts using any combination of common turnout motors. Different motor types will have different wiring issues.

  • Tortoise or other Stall Motor machines — stall motors, like the Circuitron Tortoise or Switchmaster, are the most current efficient motors available. You need relays to run a stall motor machine with a microcontroller.
  • Coil Motors — these tend to be power hungry, and potentially sensitive to wire run length. You’ll use relays to run coil motors; you may need a charged capacitor to provide the current “rush” needed to activate the coils.
  • Servo Motors — servos are run using PWM (Pulse Width Modulation ), and wiring distance can affect servo performance. We recommend that wire length between the PWM driver board and each servo be limited to 18″. We recommend that the wire length from the microcontroller to the PWM driver board be limited to 24″.

Signals, Lighting, and other Layout Objects #

Each Client node can support up to 16 signal heads with up to 3 aspects. Signals present wiring issues that tend to drive where you locate your Client Nodes. Signals, relays and general lighting use the same output port system, and are collectively limited to 256 total objects per LCN.

Like everything else, lighting is affected by wire length. If you work in N or Z scale, you very likely use ultra thin magnet wire for things like signals and structure lighting. Magnet wire is hard to manage in long runs, so the ability to terminate the wires nearby is important.

Digital input and output ports are provided by duinoNodes attached to the Layout Control Node. Each board hosts 8 ports; boards are designed to chain together, by wire or by stacking, allowing placement of ports where layout wiring is located.

The DNIN8 Input duinoNode is used for digital inputs such as buttons, switches, digital sensors and other compatible switching devices.

The DNOU8 Output duinoNode provides digital outputs to run relays, simple dc motors, panel indicators, signals and layout lighting.

Both types of duinoNodes can be stacked up to 6 boards high, providing up to 48 ports in a single stack. Both boards have an identical 77 mm x 45 mm footprint. IO chains increase LCN reach and flexibility.

A Practical Example #

Consider a basic HO layout on a 4 x 8 base:

A “basic” HO Scale layout on a 4×8 sheet of plywood doesn’t mean boring!

“Basic” is a term of art in this case because here you have a standard over/under track arrangement, enhanced with a passing siding on the left, a mountain tunnel with ends at different elevations, and a little town/industrial area with team tracks reaching into the interior. Perhaps a passenger station as well. That offers several interesting modeling and lighting opportunities.

You could divide the track into 7 or 8 isolated blocks, then add signals for a basic ABS signal system that automatically responds to block occupancy and turnout state. In the example, I designated 7 blocks and sited 9 signals to go with the 4 turnouts in the plan. Managing that is within the capabilities of a single Client Node.

However, the plan is twice as big as a standard LCN envelope. Remember that the “envelope” is a rule-of-thumb recommendation, not a straight jacket! This example illustrates how to think about LCN distribution, the physical limits of an LCN and the ways those physical limits are designed to be stretched.

Wiring Reach #

You might think that 9 signals with 3 aspects, requiring 27 output ports, is the major problem for this layout. You would be mistaken if you did because DNOU8 Output duinoNodes can be placed where needed on the layout, then linked into a single chain with up to 3′ between each board. Further,the boards stack so that you can concentrate ports where needed.

The issue this layout presents is specifically related to turnout motors. Servo motors would be a problem on this layout because the turnouts are spread across the layout. Servos have to be within 18″ of the PWM driver board — which keeps them within the standard envelope. On this layout, you would need 2 Client Nodes to run all 4 servos because of the distances involved.

Tortoise and coil machines can be further from the Client Node because they rely on DNOU8 I/O boards (running DPDT relays) to function; and DNOU8 boards can be located where needed.

Making Decisions #

So in this case, the turnout motor choice is an important factor, if not the most important factor, in deciding Layout Control Node coverage. If you prefer servos, you’ll need two Clients. Otherwise one Client should be adequate in this situation. LCOS uses relays to control stall motor and coil — relays can be attached to any nearby duinoNode port.

So now we can develop our components list:

  • LC1 LCOS Starter Kit
  • If using Servos, an additional Client plus two PWM driver boards.
  • If NOT using servos, 4 standard double channel relays,
  • 5 additional DNOU8 output duinoNodes.

The LC1 LCOS Starter Kit includes a DNIN8 board for 8 digital inputs; these are intended for control panel buttons and switches attached to the master. Additional DNIN8 boards can be added as needed for the control panel. When using a Tortoise or a SwitchMaster with optional auxiliary contacts, you can connect DNIN8 ports to the auxiliary contacts so that the system can sense turnout position.

Placement >

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