Modbux v0.3.9 Modbux.Rtu.Master View Source

API for a Modbus RTU Master device.

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Functions

Returns a specification to start this module under a supervisor.

Close the Master serial port.

Configure the Master serial port.

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

Open the Master serial port.

Read and parse the last request (if the last request timeouts).

Send a request to Modbus RTU Slave.

Starts a Modbus RTU Master process.

Gets the Master state.

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async_uart_read(state, cmd)

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Returns a specification to start this module under a supervisor.

See Supervisor.

Close the Master serial port.

Configure the Master serial port.

The following options are available:

  • tty - defines the serial port to spawn the Master.
  • timeout - defines slave timeout.
  • active - (true or false) specifies whether data is received as messages (mailbox) or by calling request/2.
  • gen_opts - defines extra options for the Genserver OTP configuration.
  • uart_opts - defines extra options for the UART configuration.

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

init_arg is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state}, except that it also sets a timeout. See the "Timeouts" section in the module documentation for more information.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning {:ok, state, {:continue, continue}} is similar to {:ok, state} except that immediately after entering the loop the c:handle_continue/2 callback will be invoked with the value continue as first argument.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

  • The GenServer is disabled by configuration but might be enabled later.
  • An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

Open the Master serial port.

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read(pid)

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read(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: any()

Read and parse the last request (if the last request timeouts).

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request(pid, cmd)

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request(atom() | pid() | {atom(), any()} | {:via, atom(), any()}, tuple()) ::
  :ok | {:ok, list()} | {:error, String.t()}

Send a request to Modbus RTU Slave.

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.
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start_link(params)

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

Starts a Modbus RTU Master process.

The following options are available:

  • tty - defines the serial port to spawn the Master.
  • timeout - defines slave timeout.
  • active - (true or false) specifies whether data is received as messages (mailbox) or by calling request/2.
  • 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]).

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

{:modbus_rtu, {:slave_response, cmd, values}} 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.

Example

Modbux.Rtu.Master.start_link(tty: "tnt0", active: true, uart_opts: [speed: 9600])

Gets the Master state.

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stop(pid)

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stop(atom() | pid() | {atom(), any()} | {:via, atom(), any()}) :: :ok