Understanding NMEA 2000 Networks

Transcription

1 Slide 1 Understanding NMEA 2000 Networks Actisense - Understanding NMEA 2000 Networks

2 Slide 2 NMEA 2000 Network Requirements Power requirements Connectivity Data layer Product certification We will discuss the following areas in detail: What is required to create an NMEA 2000 network. How to power an NMEA 2000 network. Simple plug and play nature of NMEA 2000 networks. Simple description of the NMEA 2000 Data layer. Every NMEA 2000 device is required to be certified to prove to the end-customer that it is safe for use.

3 Slide 3 Minimum Network Requirements 1 x Power-T 2 x Terminating Resistors 2 x T-Pieces (one per connected device) 2 x NMEA 2000 certified devices A2K-KIT-1 To create a minimum NMEA 2000 network you will require: Power entry point : each side of the network backbone can be powered separately (as long as the ground connection is common). Terminators : It is essential that two terminators are fitted for data signal integrity. T-Pieces : One T-Piece per device, with a maximum drop cable length of 6 metres. Devices : There must always be two devices: one to transmit and one to acknowledge reception of the message. Starter : The minimum network requirements are provided in the Actisense NMEA 2000 Starter Kit (imaginatively named A2K-KIT-1).

4 Slide 4 Network Limitations Cable Type Per drop cable Sum of all drop cables Micro backbone (terminator to terminator) Mid backbone (terminator to terminator Mini backbone (terminator to terminator) Max Length 6m 72m Max Amp Power Pair Data Pair 100m 3 Amps 22 AWG 24 AWG 250m 4 Amps 18 AWG 20 AWG 250m 8 Amps 15 AWG 18 AWG The NMEA 2000 network limitations are as detailed in this table. The important points are: The 72m total drop cable limit - as this can be reached if care is not taken to minimise the lengths of all drops. The 100m maximum backbone length when using Micro-C cabling. The 3 Amps per backbone arm, giving 6 Amps total network power (when powered from the middle). To extend an NMEA 2000 network beyond 100 metres, the central section can be wired with Mid or Mini cable, as reducing the size from the centre outwards and mixing cable types is acceptable.

5 Slide 5 Physical Layer Proven, robust 12V power supplied to all low-powered devices directly from the bus Up to 2 legs to distribute the load evenly Reduces amount of cabling Standardised wiring colours Simple plug & play connectivity Easily expandable without power interruptions A quick introduction to the NMEA 2000 Physical Layer to offer a basic foundation: DeviceNet cables and connectors were chosen by the NMEA as they are robust and proven in other industries such as automotive and agriculture. Devices that require less than 1 Amp are low powered although in practice any device over 0.5 an Amp should offer an additional power method otherwise 3 Amps per arm of the network will not go far. A single insertion point, in the middle, can split the power to both arms of the network. All devices share the same data pair in the DeviceNet backbone cable. Low powered devices also share the same power pair, removing the need for additional power cabling. There is no confusion between standardised connectors and wire colours, making field-fit connections simple to create and use. DeviceNet is a multi-industry standardisation for plug and play connectors and cables. Using a pre-installed T-piece, new devices can be installed without causing interruption to any other device. Even when inserting a new T-piece, the temporary interruption in data flow is handled by devices. A new device will find its place on the network and data will continue to flow as before.

6 Slide 6 Network Power Power provided to the backbone from two isolated sources 9-16 VDC (future 9-32 VDC) All low powered devices (< 1 Amp) take power from the backbone NMEA 2000 Network Power options: Typically a single supply will be used but using a power entry point with two pairs of power wires allows for individual fuses to be installed. If two power supplies are used, both power sources must share a common ground. Current devices are rated to work with network power of 9 to 16 volts (from a nominal 12V power supply). 9V to allow for voltage drops along the backbone length, 16V to allow for when the battery is under charge. For the future, all manufacturers have agreed to make all new devices work from a nominal 24 volt power supply (with volts between 9 and 32 volts). All Actisense NMEA 2000 devices have been designed from the beginning to operate on a 24 volt network (9-32 volts). As mentioned previously, any device requiring less than a one Amp can draw their power directly from the NMEA 2000 network power. The hope is that when the network voltage is increased to 24 volts, the amount of current taken from the network will decrease through the use of switch-mode power supplies in devices.

7 Slide 7 Power T-piece Actisense A2K-MPT-1 : Multi-Power T-piece The simplest of the three Actisense NMEA 2000 power options is the A2K-MPT-1 which offers full flexibility in powering an NMEA 2000 network whilst keeping it simple and low-cost. Note the two pairs of power wires that allow the left and right sides of the network to be powered separately, through separate fuses and possibly through separate power supplies (if they share a common ground). The Male Female design was carefully chosen to allow this power T-piece to be quickly inserted in to an existing network. Simply unscrew two existing backbone cables and insert the MPT directly between them, enabling quick network upgrades when a second power supply needs to be added to boost up the network voltage at a particular point. When two (or more) power supplies are used, all power supplies need to be isolated, with their grounds connected together at one point only (refer to NMEA 0400 for specific details).

8 Slide 8 QPD-1 Quick and easy to install LED status indicator Correctly rated fuses supplied 2 Options available (GLA & PMW) Actisense QPD-1 : Quick Power Drop The QPD-1 is the most flexible Actisense NMEA 2000 power option as it provides everything needed and more: installing the correctly rated fuses (for the chosen network backbone cable) is easy, and LEDs for power feed presence, fuse status, and polarity offer a complete range of power indicators. The QPD-1 provides all the power options found in the QNB-1 without the overhead of the six drop connections. In addition to the power connection options found in the QNB-1, the QPD-1 provides two very important diodes to prevent reverse charging / back-feeding: if it becomes necessary to connect two (or more) power supplies to an NMEA 2000 network, each power connection needs to have diode protection to prevent one power source wasting energy trying to charge another. This can be likened to using an old and a new battery in a TV remote control: the new battery will waste much of its power trying to recharge the old battery instead of powering the remote. The QPD-1 has two connector options: Glands for quick and easy use with customised bulk cable lengths (removing the need for field-fit connectors and saving installation time), or PMW connectors for ease of installation with existing device connectors.

9 Slide 9 QNB-1 Quick and easy to install LED status indicators (Power, Fuses & Data) Correctly rated fuses supplied 2 Options available (GLA & PMW) Convenient in areas of high instrument density GLA variant can be used for NMEA 0183 device distribution (if all devices have isolated inputs) Actisense QNB-1: Quick Network Block The QNB-1 is the most flexible Actisense NMEA 2000 network option as it provides everything needed and more: installing the correctly rated fuses (for the chosen network backbone cable) is easy, and LEDs for power feed presence, fuse status, and polarity offer a complete range of power indicators. In addition to the indicators offered by the QPD-1, the QNB-1 has a data LED to indicate data on the network. The QNB-1 can be used as the first level of network diagnostics. In addition to powering the network, the QNB-1 also provides six drop connections, allowing up to 6 devices to be connected to the backbone. The QPD-1 has two connector options: Glands for quick and easy use with customised bulk cable lengths (removing the need for field-fit connectors and saving installation time), or PMW connectors for ease of installation with existing device connectors. This small bundle is essentially an NMEA 2000 network in a box and as such for very small networks of up to 6 devices, the QNB-1 can hold an entire network inside itself (with the addition of two 120 ohm leaded resistors across the backbone terminals). The QNB-1 is still flexible enough to allow that small network to grow in the future by expanding out of the two backbone connection glands. Ideal for an engineer to have a complete NMEA 2000 network on his desk. For limited situations (where all of the NMEA 0183 Listeners have isolated inputs) the QNB-1 can be used as a junction box for NMEA 0183 devices.

10 Slide 10 Simple Connectivity DeviceNet standard connectors provide time saving plug & play options with the added bonus of being waterproof (IP67), an obvious important requirement for the marine environment. UL Certified cabling Simple Connectivity of NMEA 2000 cabling The Actisense range of NMEA 2000 network components has been designed to make installation as quick as possible. For example, the Actisense NMEA 2000 T-pieces (A2K-T-MFF) is the only known T- piece that can be mounted flush on a bulkhead and still allow full, easy access to the connector plug especially when field fit connectors are used! This is the reason why it is so chunky. All Actisense NMEA 2000 cables and connectors have been fully tested to meet the exhaustive DeviceNet / NMEA 2000 cable specifications, including UL certification.

11 Slide 11 Fully Customisable Cable purchased in bulk reels Easily fit cables through small holes IP67 rated Field-Fit Connectors used to easily terminate custom lengths of cable and also provide strain relief Straight and right-angled connectors available for full flexibility UL Certified cabling Fully Customisable NMEA 2000 cabling Actisense NMEA 2000 Bulk cable (A2K-BULK-100M) is provided in 100m lengths, the maximum allowed for a Micro-C backbone. The Actisense Field-Fit Connectors (A2K-FFC-xx) have been designed to meet the DeviceNet standard and perfectly compliment the Actisense Bulk Cable for fully customisable network installation lengths.

12 Slide 12 NMEA 2000 Incorrect Installation NMEA 2000 Incorrect Installation Whilst supporting our customers we were made aware of this installation where the installer wished to separate one section of the network power. The installer reported a serious issue with communication between the two power sections of this network as asked Actisense for help in diagnosing the issue. This slide highlights exactly what was happening in the power pair and why communication between the two sections of the network was impossible. CAN Bus / NMEA 2000 communications actually require 3 signals/wires to be common between all devices on the network in order for data to be shared: CAN Hi, CAN Lo and just as important, power ground (or NET C). Actisense has documented a number of other bad installations using similar diagrams please ask Actisense Support if you would like to see them.

13 Slide 13 NMEA 2000 Correct Installation NMEA 2000 Correct Installation The diagram shows a simple double-fused battery being used to power the two arms of the NMEA 2000 network using an Actisense A2K-MPT-1. The alternative shown is to use the Actisense QNB-1 as the power entry point but an Actisense QPD-1 can be used in exactly the same way if the 6 device drops of the QNB-1 are not required at that point in the network. As previously mentioned, the two arms of the network can be connected/powered from two different batteries/power supplies if they have a common ground (-ve supply) connected at a single point (refer to NMEA 0400 for full details).

14 Slide 14 NMEA 0183 Wiring 5 Channel Multiplexer = Channel Amplifier / Buffer = 190 Easy to create ground loops Difficult to document Difficult to expand NMEA 0183 network wiring In an effort to compare installation costs between NMEA 0183 and NMEA 2000, this example helps to highlight that almost 400 is spent on an NMEA 0183 Multiplexer and Buffer even before considering the cost of cabling to ensure all data sources are combined, isolated and protected. As every device requires its own cable run from Talker to Listener, there is a large amount of cable required. It is labour intensive to run all of that cable, which is another expense that is sometimes forgotten. All that cable also adds more weight to the vessel, yet another downside to NMEA 0183 installations that is hidden and sometimes forgotten. Keeping track of the multitude of NMEA 0183 wiring (and documenting it correctly) as the vessel ages can be a thankless task that only the very dedicated continue to do. This can mean that future updates have to start with the painful task of trying to understand what the current network is before anything new can be added. If there is spare capacity on a Multiplexer or Buffer then adding another device can be simple. If not, then another network component will need to be purchased, adding further cost.

15 Slide 15 NMEA 2000 Wiring NMEA 2000 network wiring One backbone cable creates the whole network (excluding power cables for high powered devices) greatly reducing the length of cabling required. As the backbone is the data multiplexer and buffer, multiple Talkers and Listeners can be added, saving the cost of those interface devices immediately. As NMEA 2000 specifies that all devices have an isolated data connection, there is no issue with ground loops to overcome either. Installation time can be cut considerably. Whilst NMEA 2000 cabling can look to be more expensive when looking at its per metre cost, money will be saved when considering a whole network both in cable costs and installation costs. Interestingly a sometimes forgotten benefit is the saving in actual weight.

16 Slide 16 Space Reduction NMEA 0183 NMEA 2000 Space Reduction in cable conduits For boat builders, cable conduits for NMEA 2000 networks can be reduced in size, possibly increasing flexibility in other vessel design areas. For installers on existing vessels, once the old NMEA 0183 cable has been removed, the cable conduits will be far less crammed and easier to run new cables through.

17 Slide 17 Labour Reduction NMEA 0183 NMEA 2000 Labour reduction between NMEA 0183 and NMEA 2000 NMEA 0183 cabling can quickly become unwieldly and messy unless extra care and time is spent during installation. In contrast, NMEA 2000 cabling is easier to keep neat and understandable.

18 Slide 18 Weight & Price Reduction NMEA 0183 NMEA devices requiring 275 metres of 6 core cable = 1100 (@ 4/m) = 20 Kg 15 devices requiring 24 metres of 4 core cable and 15 T-pieces = 490 (2m x 6, 1m x 12) = 2.4 Kg Weight & Price Reduction Whereas the cable used to wire NMEA 0183 devices can appear to be lower cost when compared per metre with NMEA 2000 cabling, once you start to understand the reduction in cable lengths, the cost of the two installations becomes clear: NMEA 2000 can actually be the lowest cost solution, even before including the installation time savings. The NMEA quotes in their presentations an Italian boat builder who reportedly found that their new vessels with an equivalent NMEA 2000 network required 3 weeks less labour to lay the cables and the yacht was over 150 kilos lighter so they are very happy with the move from NMEA 0183.

19 Slide 19 Data Layer Binary 250k Baud Bi-directional data transfer Prioritised data transmission 100% of the bandwidth is available (no loss due to collisions) Send large amounts of data, quickly PGN information available from PGN data field information contained in Appendix B To complement the Physical Layer introduction earlier, this is a quick introduction to the NMEA 2000 Data Layer to offer a basic foundation: All NMEA 2000 messages are binary and are not human readable (unless you are Neo from the Matrix). At 250k baud, NMEA 2000 data is 50 times faster than NMEA 0183 data. An NMEA 2000 network removes all of the issues with creating bi-directional connections present with NMEA 0183 networks. High priority NMEA 2000 messages (such as vital navigation data) are guaranteed to be sent/delivered before lower priority messages (such as satellites-in-view data). CAN Bus and NMEA 2000 is an extremely reliable combination for critical data transfer and control that can use all 100% of the available bandwidth. PlugFest tests have proven that an NMEA 2000 network can still perform normally with a load approaching very close to 100%. With its much higher bandwidth, NMEA 2000 can transfer a very large amount of commands and data. The NMEA issues the top-level information about all PGNs on their website for everyone to view. This includes the names of all the fields in each PGN. NMEA 2000 Appendix B contains the fine details of every PGN field, making it the only part of the standard a software developer requires to know to create their own software application.

20 Slide 20 New Functionality Engines & EMU-1 Monitor your engines sensors from your MFD Up to 6 gauges, 4 alarms and 2 tacho inputs Dual engine monitoring Fully configurable Award winning and NMEA 2000 certified New Functionality for Engines available in NMEA 2000 The only accepted NMEA 0183 sentence for monitoring engines is RPM. Whilst XDR can be used for temperature and pressure, there are very few NMEA Listeners that understand it so use of that sentence is very limited. NMEA 2000 opens up the possibility to monitor temperature, pressure, RPM, battery voltage, fluid levels and a wide range of alarms on the largest range of NMEA 2000 MFDs. The Actisense EMU-1 can : Connect directly to the sensor or the gauge. When the gauge is to remain in-circuit, it is easiest to connect directly to the back of each gauge for both the gauge input and for the EMU-1 power. When the gauge is to be removed from circuit, the EMU-1 will automatically take over powering the sensor, it needs to be connected close to the sensors and can be powered from any convenient power source. Connect temperature, pressure or fluid level senders/gauges to the 6 gauge inputs. Connections to the 4 alarm inputs can create automatic alarm messages that an MFD will sound to alert the operator. One or two engine RPM signals can be connected to the two tacho inputs. Monitor up to two engines using a single EMU-1, if 3 gauge and 2 alarms per engine is acceptable and the two engines share the same battery power. Be configured and Flash updated over the network for extreme ease of installation and maintenance, using the Actisense NGT-1. The EMU-1 won the BMEA s (British Marine Electronic Association) Product of the Year in 2013 and is fully NMEA 2000 certified. The Actisense NGT-1 won the same award in 2010, as did the Actisense NGW-1 in 2011.

21 Slide 21 EMU Config Tool Demonstration EMU Config Tool demonstration Connect to EMU on the NMEA 2000 network via an NGT-1. Show how a gauge configuration is made for temperature, pressure, fluid level. Show how an alarm configuration is made for various +ve going and ve going alarm signals. Show how the RPM configuration is made and send new configuration to the EMU-1.

22 Slide 22 NMEA Certification Any device claiming NMEA 2000 Approved must be certified, including cables and connectors Certification tool provided by the NMEA Ensures devices can safely co-exist on the same network Be careful of NMEA 2000 Compatible or Works With NMEA 2000 Certification All NMEA 2000 certified devices are listed on the NMEA s website, so an installer unsure of a device can check if it is listed. NMEA 2000 Certification Tool hardware consists of an isolated CAN to PC interface gateway. Performs 40 manual tests and 60 automated tests across 25 functional categories (detailed in Appendix C) to ensure that the device meets all requirements of the NMEA 2000 standard. In addition to this manufacturer s will bring their devices to a closed ConnectFest where new products from all manufacturers can be tested (warts and all) on an NMEA 2000 network that will also be stressed to its limits. Products that say NMEA 2000 Compatible or Works With NMEA 2000 should only be used with caution, especially from a small manufacturer. If the device cannot be NMEA 2000 certified even though it passes the NMEA 2000 Certification Tool tests and it is from a major manufacturer, this could be due to one or both of these reasons: Daisy-chaining when a device has two NMEA 2000 connectors on it to allow one device to be daisy-chained to a second device (instead of connecting all devices directly to the NMEA 2000 backbone). Internal terminators when a terminator can either be manually included (via jumper) or electronically included (via a menu option or other method). The NMEA committee has deemed that whilst these two features can sometimes be useful, they can be detrimental to the health of an NMEA 2000 network so they cannot be condoned.

23 Slide 23 OneNet Extending NMEA 2000 The NMEA OneNet Network Standard is an OPEN industry standard. It contains a Physical and Network layer standard based upon the IEEE Ethernet Local Area Network. This OneNet Standard preserves and is based upon existing and future NMEA 2000 Messages (PGNs). The primary goals of OneNet are: To allow transport of NMEA 2000 Network Messages over IP in a standardized manner To complement and interoperate with the established industry standard NMEA 2000 Network To establish standardized Gateway rules between NMEA 2000 and OneNet To support high bandwidth applications such as video data transport (which is not possible using NMEA 2000 Network) OneNet Extending NMEA 2000 Notes in addition to that stated on the slide: Actisense have been on the OneNet working committee since 2010 with the aim of keeping it achievable to all manufactures. The current time line is to publish the first release by the end of 2015 so that manufacturers can start to create products next year (2016). Once released OneNet will help reduce the disparate collection of current solutions that are trying to meet the desire to share NMEA 2000 and NMEA 0183 data over Ethernet. With OneNet comes the ideal to continue to keep the marine industry open and reduce the amount of manufacturer proprietary data.

24 Slide 24 Any Questions? If there are any questions, please feel free to ask.