Returns a specification to start this module under a supervisor.

See Supervisor.

@spec get_db(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: any()

Gets the current state of the Slave DB.

Callback implementation for GenServer.init/1.

@spec raw_write(atom() | pid() | {atom(), any()} | {:via, atom(), any()}, any()) ::
  any()

Send a raw frame through the serial port.

@spec request(atom() | pid() | {atom(), any()} | {:via, atom(), any()}, any()) ::
  any()

Updates the state of the Slave DB.

cmd is a 4 elements tuple, as follows:

• {: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.

@spec start_link(keyword()) :: :ignore | {:error, any()} | {:ok, pid()}

Starts a Modbus RTU Slave process.

The following options are available:

• tty - defines the serial port to spawn the Slave.
• gen_opts - defines extra options for the Genserver OTP configuration.
• uart_opts - defines extra options for the UART configuration (defaults:

  [speed: 115200, rx_framing_timeout: 1000]).

• model - defines the DB initial state.
• active - (true or false) enable/disable DB updates notifications (mailbox).

The messages (when active mode is true) have the following form:

{:modbus_rtu, {:slave_request, payload}}

or

{:modbus_rtu, {:slave_error, payload, reason}}

The following are some reasons:

• :ecrc - corrupted message (invalid crc).
• :einval - invalid function.
• :eaddr - invalid memory address requested.

Model (DB)

The model or data base (DB) defines the slave memory map, the DB is defined by the following syntax:

%{slave_id => %{{memory_type, address_number} => value}}

where:

• slave_id - specifies a unique unit address from 1 to 247.
• memory_type - specifies the memory between:
  • :c - Discrete Output Coils.
  • :i - Discrete Input Contacts.
  • :ir - Analog Input Registers.
  • :hr - Analog Output Registers.
• address_number - specifies the memory address.
• value - the current value from that memory.

Example

model = %{80 => %{{:c, 20818} => 0, {:hr, 20818} => 0}}
Modbux.Tcp.Server.start_link(model: model, port: 2000)

@spec state(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: any()

Gets the Slave state.