Getting Started with RR-CirKits Signal-LCC: A Beginner's Guide

A comprehensive introduction to configuring your first LCC signal node using JMRI

---

Introduction

If you're new to model railroad signaling, the idea of setting up an automated signal system might seem daunting. However, with the RR-CirKits Signal-LCC node and JMRI software, you can create a realistic, prototype-accurate signaling system for your layout. This guide will walk you through everything you need to know to get started, even if you've never heard of LCC or JMRI before.

By the end of this article, you'll understand:

• What LCC is and why it matters
• The hardware components of the Signal-LCC node
• How to wire your first signal
• How to configure the node using JMRI's CDI tool

---

What is LCC?

LCC (Layout Command Control) is an NMRA standard for connecting and controlling model railroad accessories. Think of it as a common language that allows different devices on your layout—signals, turnouts, block detectors, and control panels—to communicate with each other without needing a central computer running all the time.

The beauty of LCC is that devices can talk directly to each other. A block occupancy detector can tell a signal to change from green to red without any intermediate computer processing. This is called "peer-to-peer" communication, and it makes your layout more reliable and responsive.

Key LCC Concepts for Beginners

| Term | What It Means | |------|---------------| | Node | A single device connected to the LCC network. The Signal-LCC is a node, as is a block detector or USB interface. | | EventID | A unique number that represents something happening on your layout, like "Block 5 is occupied" or "Signal 101 should show red." | | Producer | A node that sends out EventIDs when something happens (like a block detector sensing a train). | | Consumer | A node that listens for EventIDs and takes action (like a signal changing color). | | CAN Bus | The physical cable network that connects all your LCC nodes together, using standard Ethernet-style cables. | | CDI | Configuration Description Information—the built-in configuration interface that every LCC node provides. |

Why EventIDs Matter

Events are the heart of LCC communication. Unlike older systems that use simple on/off signals, LCC uses unique 64-bit EventIDs for every action. This means:

• No address conflicts: Every EventID is globally unique
• Unlimited connections: Any number of devices can respond to the same event
• Easy expansion: Add new devices without reconfiguring existing ones
• Self-documenting: Events can carry meaningful descriptions

---

Meet the Signal-LCC Node

The RR-CirKits Signal-LCC serves as a logic processing unit—the "brain" for controlling signals on your LCC network. It's a compact, powerful board that can control multiple signal heads while also providing general-purpose input/output capabilities.

Key Specifications

| Feature | Specification | |---------|---------------| | Input/Output Lines | 8 configurable I/O pins | | Signal Drivers | 16 dedicated LED drivers (4 signal heads × 4 LEDs each) | | I/O Current Rating | ±25 milliamps per pin at 5V logic level | | Board Power Draw | 20 milliamps (plus connected loads) | | Network Connection | Dual RJ45 jacks for daisy-chain CAN bus | | Configuration | Via JMRI DecoderPro 4.8 or later |

Hardware Variants

RR-CirKits offers two versions of the Signal-LCC:

1. Signal-LCC-P (Pin Headers): Uses 10-pin IDC headers for connections. Ideal for permanent installations where you want clean, reliable ribbon cable connections.

2. Signal-LCC-S (Screw Terminals): Features screw terminals for direct wire connections. Better for prototyping or situations where you need to frequently change wiring.

Identifying Your Node

Every Signal-LCC has a unique Node ID printed on a label on the bottom of the board and on the packaging. This ID (which looks something like 05.01.01.01.22.00) identifies your specific node on the network. You'll need this when configuring the node in JMRI, so keep track of it!

---

What You'll Need

Before you begin, gather these items:

Required Hardware

• RR-CirKits Signal-LCC node (P or S version)
• LCC Power-Point (to provide power to the LCC bus)
• LCC Terminator (two required—one at each end of your network)
• RJ45 CAT5 Ethernet cables (for connecting nodes)
• Signal head(s) with LEDs
• Computer with USB port

Required Software

• JMRI DecoderPro version 4.8 or later (free download from jmri.org)
• LCC Buffer-USB or similar LCC-to-USB interface

Recommended Supplies

• 10-conductor flat ribbon cable (for Signal-LCC-P)
• IDC connectors (Insulation Displacement Connectors)
• Wire strippers and crimping tools
• Multimeter for testing

---

Understanding the Board Layout

Before wiring anything, take a moment to familiarize yourself with the Signal-LCC board layout.

Main Components

RJ45 Connectors (X1 and X2): These two jacks connect to the LCC CAN bus network. They're wired straight through, so you can daisy-chain multiple nodes together. The LCC specification requires at least 1 foot of cable between nodes, though shorter cables work for smaller layouts.

Status LEDs:

• Green (ON): Indicates the board has power
• Red (ACT): Shows network activity—flickers when data is being transmitted

Blue and Gold Buttons: Used for basic configuration and testing:

• Pressing both simultaneously enters Signal Test Mode (LEDs cycle through colors)
• Used for the Blue/Gold configuration method (advanced)

I/O Port (I/O-1): A 10-pin header for connecting to input/output devices like block detectors, push buttons, or indicator LEDs.

Signal Head Connectors (H1-H4): Four headers, each supporting one signal head with connections for:

• Common (power)
• Green LED
• Yellow LED
• Red LED
• Lunar (white) LED

Wiring Pin Layout

The I/O port uses a 10-pin connector with the following layout:

| Pin | Connection | |-----|------------| | 1 | Line 8 | | 2 | Line 7 | | 3 | Line 6 | | 4 | Line 5 | | 5 | Ground | | 6 | +5VDC | | 7 | Line 4 | | 8 | Line 3 | | 9 | Line 2 | | 10 | Line 1 |

Note: The pin numbers and line numbers run in opposite directions! Pin 1 is Line 8, and Pin 10 is Line 1. This is a common source of confusion, so double-check your wiring.

---

Wiring Your First Signal

Let's walk through connecting a basic three-color signal head to the Signal-LCC.

Step 1: Determine Your LED Type

First, identify whether your signal uses common anode or common cathode LEDs:

• Common Anode: All LED positive leads connect together (most newer signals)
• Common Cathode: All LED negative leads connect together (older signals like Atlas)

The Signal-LCC has a jumper labeled CA/CC that must be set correctly:

• CA position: For common anode signals (default)
• CC position: For common cathode signals

Important: Most modern signals, including Atlas signals manufactured recently, use common anode wiring. Older Atlas signals and Tomar searchlight signals typically use common cathode. Check your signal's documentation!

Step 2: Connect the Signal Head

For a standard three-color signal on header H1:

1. Common wire → H1 Common pin
2. Green LED wire → H1-G pin
3. Yellow LED wire → H1-Y pin
4. Red LED wire → H1-R pin
5. Lunar/White wire (if present) → H1-L pin

If using the Signal-LCC-P with ribbon cable:

1. Crimp an IDC connector onto the flat ribbon cable
2. Ensure the red stripe on the cable aligns with pin 1
3. Press the connector firmly onto the header

Step 3: Connect Power and Network

1. Connect an RJ45 cable from your LCC Power-Point to one of the Signal-LCC's RJ45 jacks
2. If you have additional nodes, daisy-chain them using the second RJ45 jack
3. Install terminators at both ends of your LCC network

Step 4: Verify Power

When powered correctly:

• The green ON LED should illuminate
• The red ACT LED should flicker occasionally (showing network activity)

If the Gold LED is blinking rapidly, the node is having trouble establishing itself on the network—check your cable connections and terminators.

---

Connecting to JMRI

Now that your hardware is wired, it's time to configure the Signal-LCC using JMRI.

Step 1: Install and Configure JMRI

1. Download JMRI from jmri.org if you haven't already
2. Install and launch DecoderPro or PanelPro
3. Go to Edit → Preferences → Connections
4. Add a new connection for your LCC interface (e.g., "LCC via USB")
5. Select the appropriate COM port for your LCC Buffer-USB
6. Save and restart JMRI

Step 2: Open the Node Configuration

1. From the main menu, select OpenLCB → Configure Nodes
2. A window will appear showing all detected LCC nodes on your network
3. Find your Signal-LCC in the list (identified by its Node ID)
4. Click on the node, then click Open Configuration Dialog

Step 3: Understanding the CDI Interface

The CDI (Configuration Description Information) window may look overwhelming at first—it's a long form with many options. Here's the key insight: you don't need to configure everything. Most settings can remain at their defaults.

The CDI is organized into collapsible segments:

| Segment | Purpose | |---------|---------| | Identification | Manufacturer info and firmware version | | User Identification | Your custom name and description for this node | | Lines (I/O-1) | Configure the 8 general-purpose I/O lines | | Masts | Configure signal mast rules and appearances | | Logic | Set up internal logic for automatic signal control | | Track Circuits | Configure virtual code lines between masts |

Pro Tip: Click the small arrows to collapse segments you're not currently working on. This makes the interface much more manageable!

Step 4: Name Your Node

Start with the User Identification segment:

1. Click Read to see current values
2. Enter a meaningful Name (e.g., "Staging Yard East")
3. Add a Description (e.g., "Controls masts 101L and 102L")
4. Click Write to save your changes

These names will appear in the node list, making it easy to identify nodes later.

---

Configuring a Basic Signal

Let's configure a simple block signal that shows:

• Red (Stop) when the block ahead is occupied
• Green (Clear) when the block ahead is clear

Understanding Rules vs. Aspects

The Signal-LCC uses railroad prototype terminology:

• Rule: The name of a signal indication (e.g., "Rule 281 - Clear")
• Aspect: The visual appearance of the signal (which lights are lit)
• Mast: A complete signal installation (may have multiple heads)

Step 1: Configure the Mast

1. Expand the Masts segment in the CDI
2. Select the Mast 1 tab
3. Set Mast Processing to "Normal"
4. Enter a Mast ID (e.g., "101L" for milepost 101, left side)
5. If your signals have incandescent-style fade effects, set Lamp Fade to "Incandescent"

Step 2: Define Signal Rules

Under the Mast configuration, you'll find Rules tabs. For our simple signal:

Rule 1 (Stop):

1. Select the Rule 1 tab
2. Choose a Name such as "Stop" or "Rule 292"
3. Set Track Speed to "Stop"
4. Note the (C) Event to Set Aspect field—this is the EventID that will trigger this aspect

Rule 2 (Clear):

1. Select the Rule 2 tab
2. Choose a Name such as "Clear" or "Rule 281"
3. Set Track Speed to "Clear/Proceed"
4. Note this rule's EventID as well

Step 3: Configure Aspect Appearance

Now tell the Signal-LCC which LEDs to light for each rule:

For Rule 1 (Stop):

1. Find Lamp A and set it to "H1-R Steady" (Head 1, Red, Steady)
2. Leave other lamps as "None"

For Rule 2 (Clear):

1. Set Lamp A to "H1-G Steady" (Head 1, Green, Steady)
2. Leave other lamps as "None"

Step 4: Create EventID Links

The final step is connecting your signal to something that will control it. You have two options:

Option A: Control from JMRI

1. In JMRI, create a new Signal Mast that sends the appropriate EventIDs
2. Use JMRI's Signal Mast Logic to control the signal based on block occupancy

Option B: Direct LCC Control

1. Configure a block detector node to produce events for "occupied" and "unoccupied"
2. Copy those EventIDs into the Signal-LCC's Logic section
3. Set up logic rules that send the appropriate aspect events

---

Using the Logic Section

The Signal-LCC includes 32 internal logic statements that can automatically calculate signal aspects based on conditions like block occupancy and turnout position.

Logic Basics

Each logic statement can:

• Watch for two different events (called Variables)
• Apply a logical operation (AND, OR, XOR)
• Produce up to four events when the condition is true (or false)
• Include time delays

Example: Automatic Block Signal Logic

Here's how to set up a signal that automatically shows Stop when Block 5 is occupied:

1. Open the Logic segment
2. Select Logic 1
3. Enter a Description: "Block 5 → Stop"
4. Set Group Function to "Last (Single)" for a standalone rule

Configure Variable 1:

• Set Variable Source to "Events"
• Paste the "Block 5 Occupied" EventID into Event to set True
• Paste the "Block 5 Clear" EventID into Event to set False

Configure the Action:

• Set Action when True to "Send then Evaluate Next"
• In Action 1, paste the "Show Stop" EventID from your mast configuration

Configure False Condition:

• Set Action when False to "Send then Evaluate Next"
• In Action 1, paste the "Show Clear" EventID

Now your signal will automatically respond to block occupancy without any computer intervention!

---

Tips and Troubleshooting

Common Issues and Solutions

Signal stays dark:

• Check the CA/CC jumper setting matches your LED type
• Verify power is connected (green LED on)
• Test with Signal Test Mode (press Blue + Gold buttons together)

Node not appearing in JMRI:

• Verify LCC cables are properly connected
• Check that terminators are installed at network ends
• Ensure your LCC-USB interface is working

Changes don't take effect:

• Always click Write after changing values
• Some changes require a node reboot (use More → Reboot)

EventIDs not working:

• Double-check you've copied the complete EventID
• Verify the producing node is actually sending events (watch the Activity LED)

Best Practices

1. Document everything: Keep a spreadsheet of your EventIDs and what they mean
2. Use meaningful names: The Name and Description fields help you remember what each node does
3. Back up your configuration: Use JMRI's Backup button before making major changes
4. Start simple: Get one signal working before adding complexity
5. Check the manual: The RR-CirKits manual at rr-cirkits.com has detailed examples

Layout Power Sense Feature

The Signal-LCC has an optional "Layout Power Sense" input. When connected to your layout's 5V power:

• If layout power is lost (due to a short circuit, emergency stop, etc.), the signals lock in their last state
• This prevents signals from flickering or going dark during brief power interruptions
• When power returns, normal operation resumes

---

Next Steps

Once you have basic signals working, consider these enhancements:

Advanced Signal Types

• Position Light Signals (PRR style): Use multiple LEDs per aspect
• Searchlight Signals: Configure the "H2 Flicker" effect for realistic red flash between aspects
• Color Position Lights (B&O style): Use the "Tumble Down" effect for dropping to Stop

Virtual Track Circuits

The Signal-LCC can simulate prototype "code line" circuits that pass speed information between signals. This allows one signal to know what aspect the next signal is displaying—essential for proper approach signals.

Integration with JMRI

• Use JMRI's Signal Mast Logic for complex interlocking calculations
• Create CTC panels that interact with your LCC signals
• Set up automatic block signaling for your entire layout

---

Additional Resources

• RR-CirKits Website: rr-cirkits.com - Latest manuals and firmware updates
• JMRI Documentation: jmri.org - Comprehensive guides for signal configuration
• OpenLCB Group: openlcb.org - Technical specifications and community knowledge base
• Signal-LCC Video Guide: YouTube - Visual walkthrough of wiring and setup

---

Conclusion

The RR-CirKits Signal-LCC is a powerful tool for adding realistic signaling to your model railroad. While the learning curve may seem steep at first, the combination of standardized LCC communication and JMRI's user-friendly configuration tools makes it accessible to modelers of all skill levels.

Start with a simple two-aspect signal, get comfortable with the configuration process, and then gradually add more complex logic and signal types. Before you know it, you'll have a fully automated signal system that rivals the prototype!

---

This article was created with reference to the RR-CirKits Signal-LCC manual (Revision C, September 2024), the JMRI CDI Primer from OpenLCB.org, and the Signal-LCC wiring overview video.