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B&G Fastnet Bus information | Oppedijk.com
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<div> This is the general information on the bus used by B&G (Brookes and Gatehouse) H2000 and H3000 systems (and probably also the H1000)</div> <div> </div> <h2><a name="TOC-Fastnet-cable"></a>Fastnet cable</h2> <div> <div>The system is terminated by a 100 ohm resistor at each end, total resistance when measured between White and Green should be 50 ohms</div> <div> </div> <div>The cable is using 4 strands and the screen on the H2000 and H3000 system.</div> </div> <div>RED = 12 Volts DC</div> <div>BLACK = 0 Volts</div> <div>WHITE = Network Data +ve</div> <div>GREEN = Network Data -ve </div> <div> </div> <div>For H1000, a connector is used, front view of male connector:</div> <div>1 = 12V</div> <div>2 = Busy</div> <div>3 = Fastnet-</div> <div>4 = Fastnet+</div> <div>5 = 0V<br /><img width="180" height="165" src="/media/Default/BandG/fastnet2-connector.png" /></div> <h2><a name="TOC-Fastnet-Bus-specifications"></a>Fastnet Bus specifications</h2> <div>(Thanks to Tom Lafleur for all the information)<br />The bus is on a 28k8 speed, with odd parity and 2 stopbits<br />Green and White are the data lines, together with a 12V and a Ground signal.<br /> </div> <div>Data is sent on a system which looks a bit like CAN.</div> <div><br />Complete layout of a Serial TTL to Fastnet <a href="/media/default/downloads/BGFastNet1.pdf" target="_blank">schematic</a> (thanks to Tom for all the work) also be aware to change the terminators on the network from 100 ohm to 120-180 ohm. This is to make different kinds of CAN receivers to work. total Resistance should be 60-90 ohm (instead of the normal 50 ohm)</div> <div> </div> <div>Basic layout of a data frame is this:</div> <div><img width="658" height="73" alt="" src="/Media/Default/BandG/fastnetData.png" /></div> <div> </div> <div>TO & FROM: list of source and destination <a href="fastnet-node-numbers.html">node</a> addresses</div> <div>SIZE: size of data, without headers and checksums</div> <div>COMMAND: list of all <a href="fastnet-commands.html">commands</a>, mostly 0x01 is used</div> <div>HEADER CHECKSUM: this is 0x100 - the total of all the bytes in het header modulo 8 (or: header data modulo 8 + checksum = 0)</div> <div>CHANNELNR: list of all the <a href="fastnet-channels.html">channels</a> being used</div> <div>FORMAT: this is the format byte, determines decimal dot and format</div> <div>DATA: mostly 2 or 4 bytes</div> <div>FULL CHECKSUM: this is 0x100 minus all the bytes modulo 8 (or: all data modulo 8 + checksum = 0)</div> <h2><a name="TOC-Fastnet-demo-decode"></a>Fastnet demo decode</h2> <div>This is an example string recorded on the bus:<br />ff 05 14 01 e7 1d 61 00 58 1c 51 01 df 87 06 00 be e8 e8 86 06 00 be e8 e8 a8</div> <div> </div> <div><strong>split it into header and checksum parts:</strong></div> <div><span style="background-color: #ff9900;">ff 05 14 01</span> <span style="background-color: #ffff00;">e7</span> 1d 61 00 58 1c 51 01 df 87 06 00 be e8 e8 86 06 00 be e8 e8 <span style="background-color: #ffff00;">a8</span></div> <div>ff = broadcast to all</div> <div>05 = from wind/depth</div> <div>14 = data in body part, 14hex = 20 dec = 20 databytes</div> <div>01 = fastnet command, general data send</div> <div>e7 = checksum header (header data modulo 8 + checksum = 0)</div> <div>a8 = full frame checksum(all data modulo 8 + checksum = 0)</div> <div> </div> <div><strong>decode body parts</strong></div> <div>the first byte is the channel, the second is a mask to display the data? the rest is data<br />ff 05 14 01 e7 header<br /> <span style="background-color: #ff9900;">1d</span> <span style="background-color: #ffff00;">61</span> <span style="background-color: #00ffff;">00 58</span> 1d = air temp C, format = 61, data = 0058 hex == 88dec == 88/10 = 8.8 degrees celsius<br /> <span style="background-color: #ff9900;">1c</span> <span style="background-color: #ffff00;">51</span> <span style="background-color: #00ffff;">01 df</span> 1c = air temp F, format = 51, data = 01df hex == 479dec == 479/10 = 47.9 degrees fahrenheit (= 8.8 degrees celsius)<br /> <span style="background-color: #ff9900;">87</span> <span style="background-color: #ffff00;">06</span> <span style="background-color: #00ffff;">00 be e8 e8</span> 87 = barometric pressure, format = 06, raw data is 4 letters, value " Off"<br /> <span style="background-color: #ff9900;">86</span> <span style="background-color: #ffff00;">06</span> <span style="background-color: #00ffff;">00 be e8 e8</span> 86 = barometric pressure trend, format = 06, raw data is 4 letters, value " Off"<br />a8 checksum</div> <div><strong>more examples</strong></div> <div>41 91 02 71 41 = Boatspeed, format = 91, data = 0271 hex = 625 decimal = 625/100 = 6.25 knots</div> <div>4d 61 00 04 4d = AWS knots, format = 61, 0004 hex = 4 dec = 04 knots<br /> 4f 61 00 02 4f = AWS m/s, format = 61, 0002 hex = 2 dec = 02 m/s (= 4 knots)</div> <div> </div> <div><strong>format byte</strong></div> <div>the format byte (e.g. 61) is a bit pattern, so transform this hex value to binary 61
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