Wiring a PC running Expedition to a DMK Box
Many folks would like to broadcast the performance numbers like Target Boatspeed and Percent Polars being generated by Expedition to on deck apps like Ventus Navigation and the NKE App. Using this data can help a driver get feedback to unlock their best boatspeed. This is especially useful for boats that do not already have a performance processor. In another article I talked about connecting the DMK Box and Expedition via WiFi. This time I will explain how to hard wire a PC to a boat's 0183 Instruments and DMK box so that you can broadcast the data on deck tablets.
Many computers, especially laptops, no longer have a network serial port to connect. In these installations it is important to have a USB to Serial converter to make the connection. You can purchase one from Radio Shack or most consumer electronics stores. After you have the adapter you must wire the serial port to the boat and then connect it to the converter to open up a communications port with the instruments and the DMK Box. You can purchase a NMEA 0183 to RS 232 cable or make your own. Pin 2 is Data In, Pin 3 is Data Out, and Pin 5 is NMEA Ground.
On my boat I have Raymarine instruments so I convert them from Seatalk to Raymarine using a Raymarine E85001. When connecting to the E85001 I split the NMEA 0183 out to two leads and connected the leads to the Secondary 0183 port on the DMK Box, and to Data In (Pin 2) on the Serial cable. Next I connected the Data Out (Pin 3) from the Serial Cable to the Primary 0183 Port on the DMK Box. Lastly I connected the NMEA 0183 Ground from the serial cable to the NMEA 0183 (-) on the Raymarine E85001. The black and white ground wires from the DMK Box also were connected to the NMEA 0183 (-) of the Raymarine E85001. Tying all the NMEA Grounds together will ensure a good data signals to the PC and the DMK Box.
After you have made the wiring connections you will need to configure Expedition and the DMK Box to get the data flowing. My first time connecting I was using the NKE App so in Network and Serial Ports I chose NKE under instruments. This assured that the Target Boatspeed and Polar Data I wanted to see in the app was being sent by the PC. I chose 4800 Baud as my rate as this was the output rate of the E85001 and the input and output rates must match. Next I went into the DMK App and changed the Primary 0183 Port to 4800 to match the rate coming from the PC. The baud rate of either 0183 port on the DMK Box can be changed by going to Instrument List>Settings>Primary(or secondary) 0183 Baud.
After this I had both my instrument data as well as my Expedition data streaming to my tablet on deck. I can't wait to go out and do some sailing and try it out more.