baud v0.4.2 Baud
Serial port module.
alias Baud.Enum
["COM1", "ttyUSB0", "cu.usbserial-FTVFV143"] = Enum.list()
#Do not prepend /dev/ to the port name
#Try this with a loopback
{:ok, pid} = Baud.start_link([portname: "cu.usbserial-FTYHQD9MA"])
#Send data
:ok = Baud.write pid, "Hello"
#Wait data is transmitted
:ok = Baud.wait4tx pid
#Wait at least 5 bytes are available
:ok = Baud.wait4rx pid, 5
#Check at least 5 bytes are available
{:ok, 5} = Baud.available pid
#Read 4 bytes of data
{:ok, "Hell"} = Baud.read pid, 4
#Read all available data
{:ok, "o"} = Baud.readall pid
#Send more data
:ok = Baud.write pid, "World!
..."
#Wait at least 1 byte is available
:ok = Baud.wait4rx pid, 1
#Read all data up to first newline
{:ok, "World!
"} = Baud.readln pid
#Discard trailing ...
:ok = Baud.discard pid
#Check nothing is available
{:ok, 0} = Baud.available pid
#Check the native port is responding
:ok = Baud.echo pid
#Close the native serial port
:ok = Baud.close pid
#Stop the server
:ok = Baud.stop pidSummary
Functions
Returns the number of bytes available in the serial port input buffer
Closes the serial port and waits for confirmation
Enables or disables native port debug output to stderr
Discards all data in the input and output buffers of the serial port
Tests if the native port has completed all previous commands
Changes the packetization timeout
Reads count bytes
Reads all available data from the serial port up to the buffer size
Reads a line including its trailing \n
Sends an RTU command where cmd is formatted according to modbus package
Starts the serial server
Stops the serial server
Waits for at least count bytes to be available
Waits for all data to be transmitted
Writes data to the serial port
Functions
Returns the number of bytes available in the serial port input buffer.
Returns {:ok, number_of_bytes}.
Closes the serial port and waits for confirmation.
Stopping the GenServer will close the port stdio pipes the native port will exit upon detection of a closed stdio and the OS will release the serial port. All this happens automatically but also within an undefined time frame.
There are times when releasing the OS resources in a timely manner is required. In unit testing for example, you want the previous test to release the serial port before attemping to open it again in the next test (and fail).
Returns :ok.
Enables or disables native port debug output to stderr.
Returns :ok.
Discards all data in the input and output buffers of the serial port.
Returns :ok.
Tests if the native port has completed all previous commands.
Returns :ok.
Reads all available data from the serial port up to the buffer size.
Returns {:ok, data}.
Sends an RTU command where cmd is formatted according to modbus package.
cmd is one of:
{:rc, slave, address, count}read count coils.{:ri, slave, address, count}read count inputs.{:rhr, slave, address, count}read count holding registers.{:rir, slave, address, count}read count input registers.{:fc, slave, address, value}force single coil.{:phr, slave, address, value}preset single holding register.{:fc, slave, address, values}force multiple coils.{:phr, slave, address, values}preset multiple holding registers.
Returns :ok | {:ok, [values]}.
Example:
#rs485 usb adapter to modport
{:ok, pid} = Baud.start_link([portname: "cu.usbserial-FTVFV143", baudrate: 57600])
#force 0 to coil at slave 1 address 3000
:ok = Baud.rtu pid, {:fc, 1, 3000, 0}
#read 0 from coil at slave 1 address 3000
{:ok, [0]} = Baud.rtu pid, {:rc, 1, 3000, 1}
#force 10 to coils at slave 1 address 3000 to 3001
:ok = Baud.rtu pid, {:fc, 1, 3000, [1, 0]}
#read 10 from coils at slave 1 address 3000 to 3001
{:ok, [1, 0]} = Baud.rtu pid, {:rc, 1, 3000, 2}
#preset 55AA to holding register at slave 1 address 3300
:ok = Baud.rtu pid, {:phr, 1, 3300, 0x55AA}
#read 55AA from holding register at slave 1 address 3300 to 3301
{:ok, [0x55AA]} = Baud.rtu pid, {:rhr, 1, 3300, 1}Starts the serial server.
state must contain a keyword list to be merged with the following defaults:
%{
portname: "TTY", #the port name: "COM1", "ttyUSB0", "cu.usbserial-FTYHQD9MA"
baudrate: "115200", #either 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200
bitconfig: "8N1", #either 8N1, 7E1, 7O1
bufsize: 255, #the buffer size. 255 is the POSIX maximum.
packto: 0 #the packetization timeout in millis. 100 in the POSIX minimum.
#use 0 for non-blocking reads
}opts is optional and is passed verbatim to GenServer.
Returns {:ok, pid}.
Example
Baud.start_link([portname: "COM8"])