ACTISENSE NDC-4 AIS MULTIPLEXER

An NMEA 0183 multiplexer with 5 inputs and two outputs compatible with PC serial ports, preconfigured for use with an AIS system.

This Actisense™ NMEA Multiplexer / Combiner allows connection of up to five NMEA 0183 inputs, and combines them to its two fully isolated NMEA outputs.

This approach offers these major advantages:

• Completely removes the need for isolated power supplies - as the NDC-4 creates a full 2500v isolation barrier between its inputs and each of it's ISO-Drive outputs
• Enables the vessel owner complete access to all NMEA data sources, instead of the standard one device
• Any problematic or unwanted NMEA sentences can be filtered out / blocked, to help intelligently reduce the NMEA data to a manageable amount and prevent data loops
• Each NMEA input device is Opto-isolated from all other NMEA device in the system
• Significant reductions in installation cost (from reduced cable lengths and requiring only one NMEA cable to be routed around the bridge to supply the multiplexed NMEA data

The NDC-4 has two ISO-Drive outputs which are fully compatible with all standards: NMEA 0183 (RS422), RS485 and PC RS232 ports. Electrical spike protection is provided as standard on all four input channels using opto-isolators. This protects any connected equipment from most system faults; a particularly valuable benefit as equipment requiring the most data, such as a PC or chart plotter, is often the most expensive to repair or replace. The NDC-4 Data Multiplexer contains intelligent software that manages the multiplexing operation, allowing every input to have a chance of its data reaching the combined NMEA output. Tested up to and beyond a combined 400% loading of the four inputs.

Product Features

• Pre-configured for AIS : One input is set to 38,400 baud and the NMEA filter removes AIS data from the low-speed outputs.
• 5 Opto-isolated NMEA 0183 data inputs : Full galvanic Opto-isolated differential inputs that fully comply with the NMEA 0183 standard specification. This allows the input to work correctly with long cable runs, and/or in a noisy environment. This also allows the NDC-4 to offer up to 2500v of common mode voltage difference (between its input and outputs). This will prevent any ground loop damage occurring.
• 2 ISO-Drive flexible outputs : The ISO-Drive outputs are fully compatible with the RS422 (NMEA 0183), RS485 and RS232 connections on the NMEA listening device(s) the NDC-4 supplies data to, and offers total galvanic isolation of up to 1500v between the output and ground. The full-differential output ensures better quality communications and lower noise emissions on unshielded twisted pair cabling.
• Powerful processor : An ARM 32-bit microcontroller capable of 40 million instructions per second, and very large NMEA data buffers to allow smoothing of short-term peaks in the NMEA data flow.
• Flash upgradeable : The hardware's firmware (software) can be easily upgraded as and when necessary.
• Combine mode: Intelligent software filters the valid data from all active inputs, using the configured Inclusion lists, and then combines the remaining data using a simple priority system. Highest priority input (1) has the best chance of its data being added to the output combined NMEA data, and input 4 the lowest chance. This advanced user controlled system only operates as and when it becomes necessary to reduce the NMEA data outputted (triggered by very high loading of the combined NMEA output). The ISO-Drive and / or USB output will always contain all of the NMEA data (due to its higher Baud rate and bandwidth).
• Autoswitch mode: Intelligent software determines the highest priority device with valid data, based on one of three reasons - a failure to send any NMEA data, an invalid NMEA sentence checksum, or if the validity flag(s) contained within the NMEA sentence indicate that this data is not valid and should only be used with caution (for GPS and Depth data). The chosen input's data will be resent out the two ISO-Drive outputs (and USB if available), allowing two different Baud rates to be used (typically 38400 Baud and 4800 Baud).
• Very low current consumption : Ideal for small vessels with small batteries.
• Diagnostic tri-colour LED : Indicates current operation mode, volume of data being multiplexed, or if a hardware fault has been detected.
• IP66/IP68 case and grommet design : A very robust polycarbonate case with a high waterproof certification. The small case size is ideal for space restrictive applications.
• High quality angled screw terminals : The 'moving cage' type terminals make cable installation a simple and quick operation.

A USB output cable is available for this item but is not included. You should add the USB cable to the order if you are intending to use the USB port. The connector inside the NDC-4 is not a standard USB connector but a special Actisense version and only the Actisense cable will fit.