Overview

This document provides technical specifications, connection diagrams, and installation instructions for the NDC Digital Clock system synchronized via a GPS Network Time Server using RS485 communication.

Key Components and Interfaces

• NDC Clocks: Models NDC 100/4,6 and NDC 57/4,6.
• Communication Interface: RS485 protocol with 15V power supply over flat 6-wire telephone cables (RJ12-6/6 or RJ11-6/4 connectors).
• GPS Network Time Server: Housed in a plastic box, receives GPS signals and distributes time data via RS485.
• Power Supply: 230 VAC input powering the clock and time server units.
• Optional Local Temperature Sensor: Connected via RJ10-4/4 cable, cable length approximately 2 meters.

Installation Instructions

1. Remove the top cover of the Network Time Server box and disconnect the GPS receiver cable from the WAGO terminal connector.
2. Install the GPS receiver outdoors on a wall with a clear sky view.
3. Route the GPS receiver cable through the wall into the indoor location where the clock will be installed; drilling may be necessary.
4. Install the GPS Network Time Server unit indoors near the cable entry point.
5. Insert the GPS cable through the cable gland into the plastic box and reconnect wires to the WAGO terminal.
6. Connect the data cable from the 15V/RS485 clock connector to the XS1 connector on the Network Time Server box.
7. Power on the system by plugging the clock power supply into a 230 VAC outlet; the clock will synchronize automatically with GPS time.

Connection and Wiring Details

• RS485/Data Cable: Flat 6-wire telephone cable (default length 5 m, customizable up to 100 m).
• Connectors: RJ12-6/6 for 6-wire cables and RJ11-6/4 for 4-wire cables.
• WAGO Terminal Pinouts: Detailed pin assignments for GPS receiver and RS485 data lines including power (Vcc), ground (GND), and data lines (DATA+, DATA-).
• Bus Terminating Resistor: 120 Ω resistor (JP1) to be installed as needed for RS485 bus termination.

Synchronization and Communication

The system supports synchronization of multiple NDC clocks via RS485 bus connected to the GPS Network Time Server. The clocks receive time data and power over the same cable, ensuring accurate and reliable time distribution.

Additional Notes and Recommendations

• Ensure the GPS receiver has an unobstructed view of the sky for optimal signal reception.
• Use appropriate cable lengths and quality to maintain signal integrity over RS485 communication.
• Follow correct wiring color codes and connector pinouts to avoid connection errors.
• Install bus terminating resistor if the RS485 line is at the end of the network to prevent signal reflections.

Summary of Critical Parameters