avnav-seatalk1-simulator-rs232

General

The plugin simulates seatalk 1 protocol cyclic outputs via RS232. It sets the depth (DBT) and speed (STW) like ST50Plus Tridata does.

It is widely based on the seatalk remote plugin (https://github.com/wellenvogel/avnav-seatalk-remote-plugin).

Parameter

• device: e.g. '/dev/ttyUSB0'
• usbid: as alternative for devive name

Details

The Seatalk 1 protocol is simply written cyclic to the selected device. The following bytes are written to RS232:

DPT 'Depth below transducer' of 6,7 meters

• Byte 1: Command byte : 0x00 => parity bit is set to mark up the start of Seatalk protocol
• Byte 2: Attribute byte : 0x02 => LSB is the number of following bytes (n=2)
• Byte 3: First mandatory data byte: 0x00 => YZ: in feets
• Byte 4: optionially data byte 1 : 0xdd: LSB for value for 'Depth below transducer'
• Byte 5: optionially data byte 2 : 0x00: MSB for value for 'Depth below transducer' The resulting value for 'Depth below transducer' is 0x00dd/10 feets (221/10 feets = 22,1 feets = 6,7 meters).

STW 'Speed Through Water' of 10,9 km/h

• Byte 1: Command byte : 0x20 => parity bit is set to mark up the start of Seatalk protocol
• Byte 2: Attribute byte : 0x01 => LSB is the number of following bytes (n=1)
• Byte 3: First mandatory data byte: 0x3B => LSB for value for 'Speed Through Water'
• Byte 4: optionially data byte 1 : 0x00: MSB for value for 'Speed Through Water' The resulting value for 'Speed Through Water' is 0x003b/10 kn (59/10 kn = 5,9 kn = 10,9 km/h).

It is possible that these plugin and avnav-anchor-chain-simulator-rs232 plugin can share the same device (e.g. "/dev/ttyUSB_SeatalkOut")

Hardware needs

• A second USB-RS232-adapater
• A gender changer between USB-RS232-adapater of plugin avnav-seatalk1-reader-rs232 and the adapter of these plugin

Installation

To install this plugin please

• install packages via: sudo apt-get update && sudo apt-get install python3-serial
• create directory '/usr/lib/avnav/plugins/seatalk1-simulator-rs232' and
• copy the file plugin.py to this directory.

TODOs

• only tested with linux

Helpers

Setup the serial devices by their serial numbers

• Label your first USB serial device (e.g SeatalkOut)
• Connect the first USB serial device to the PC
• Get the vendorID, deviceID and serial number of the tty device (here "/dev/ttyUSB0") udevadm info -a -n /dev/ttyUSB0 | grep {idVendor} | head -n1 => ATTRS{idVendor}=="0403" udevadm info -a -n /dev/ttyUSB0 | grep {bcdDevice} | head -n1 => ATTRS{bcdDevice}=="0600" udevadm info -a -n /dev/ttyUSB0 | grep {serial} | head -n1 => ATTRS{serial}=="A10KKBM3"
• creates an udev rule mcedit sudo mcedit /etc/udev/rules.d/10-local.rules SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A10KKBM3", MODE="0666", SYMLINK+="ttyUSB_SeatalkOut"
• Continue with the next devices
• at the end the file /etc/udev/rules.d/10-local.rules may look like that SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A10KKF9V", MODE="0666", SYMLINK+="ttyUSB_SeatalkInp" SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="A10KKBM3", MODE="0666", SYMLINK+="ttyUSB_SeatalkOut"
• Use this names in avnav (e.g: "/dev/ttyUSB_SeatalkOut")