baud v0.5.7

Modbus.Rtu.Master (baud v0.5.7)

RTU Master server.

# run with: mix slave
alias Modbus.Rtu.Slave
alias Modbus.Rtu.Master

tty0 =
  case :os.type() do
    {:unix, :darwin} -> "/dev/tty.usbserial-FTYHQD9MA"
    {:unix, :linux} -> "/dev/ttyUSB0"
    {:win32, :nt} -> "COM5"
  end

tty1 =
  case :os.type() do
    {:unix, :darwin} -> "/dev/tty.usbserial-FTYHQD9MB"
    {:unix, :linux} -> "/dev/ttyUSB1"
    {:win32, :nt} -> "COM6"
  end

# start your slave with a shared model
model = %{
  0x50 => %{
    {:c, 0x5152} => 0,
    {:i, 0x5354} => 0,
    {:i, 0x5355} => 1,
    {:hr, 0x5657} => 0x6162,
    {:ir, 0x5859} => 0x6364,
    {:ir, 0x585A} => 0x6566
  }
}

{:ok, _} = Slave.start_link(model: model, device: tty0)
{:ok, mpid} = Master.start_link(device: tty1)

# read input
{:ok, [0, 1]} = Master.exec(mpid, {:ri, 0x50, 0x5354, 2})
# read input registers
{:ok, [0x6364, 0x6566]} = Master.exec(mpid, {:rir, 0x50, 0x5859, 2})

# toggle coil and read it back
:ok = Master.exec(mpid, {:fc, 0x50, 0x5152, 0})
{:ok, [0]} = Master.exec(mpid, {:rc, 0x50, 0x5152, 1})
:ok = Master.exec(mpid, {:fc, 0x50, 0x5152, 1})
{:ok, [1]} = Master.exec(mpid, {:rc, 0x50, 0x5152, 1})

# increment holding register and read it back
{:ok, [0x6162]} = Master.exec(mpid, {:rhr, 0x50, 0x5657, 1})
:ok = Master.exec(mpid, {:phr, 0x50, 0x5657, 0x6163})
{:ok, [0x6163]} = Master.exec(mpid, {:rhr, 0x50, 0x5657, 1})

Uses:

Link to this section Summary

Functions

exec(pid, cmd, timeout \\ 400)

Executes a Modbus command.

start_link(opts)

Opens the connection.

stop(pid)

Closes the connection.

Link to this section Functions

Link to this function

exec(pid, cmd, timeout \\ 400)

Executes a Modbus command.

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]} | {:error, reason}.
Link to this function

start_link(opts)

Opens the connection.

params must contain a keyword list to be merged with the following defaults:

[
  device: nil,        #serial port name: "COM1", "/dev/ttyUSB0", "/dev/tty.usbserial-FTYHQD9MA"
  speed: 9600,        #either 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200
                      #win32 adds 14400, 128000, 256000
  config: "8N1",      #either "8N1", "7E1", "7O1"
]

Returns {:ok, pid} | {:error, reason}.

Example 

  Modbus.Rtu.Master.start_link(device: "/dev/ttyUSB0")
Link to this function

stop(pid)

Closes the connection.

Returns :ok.