Modbux v0.3.9 Modbux.Tcp.Server View Source
API for Modbus TCP Server.
Link to this section Summary
Functions
Returns a specification to start this module under a supervisor.
Gets the current state of the Server DB.
Invoked to handle continue
instructions.
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
Starts a Modbus TCP Server process.
Updates the state of the Server DB.
Link to this section Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
Gets the current state of the Server DB.
Invoked to handle continue
instructions.
It is useful for performing work after initialization or for splitting the work in a callback in multiple steps, updating the process state along the way.
Return values are the same as c:handle_cast/2
.
This callback is optional. If one is not implemented, the server will fail if a continue instruction is used.
This callback is only supported on Erlang/OTP 21+.
Callback implementation for GenServer.handle_continue/2
.
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 callingSupervisor.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
.
start_link(params, opts \\ [])
View Sourcestart_link(any(), debug: [:log | :statistics | :trace | {any(), any()}], hibernate_after: :infinity | non_neg_integer(), name: atom() | {:global, any()} | {:via, atom(), any()}, spawn_opt: :link | :monitor | {:fullsweep_after, non_neg_integer()} | {:min_bin_vheap_size, non_neg_integer()} | {:min_heap_size, non_neg_integer()} | {:priority, :high | :low | :normal}, timeout: :infinity | non_neg_integer() ) :: :ignore | {:error, any()} | {:ok, pid()}
Starts a Modbus TCP Server process.
The following options are available:
port
- is the Modbux TCP Server tcp port number.timeout
- is the connection timeout.model
- defines the DB initial state.sup_otps
- server supervisor OTP options.active
- (true
orfalse
) enable/disable DB updates notifications (mailbox).
The messages (when active mode is true) have the following form:
{:modbus_tcp, {:slave_request, payload}}
Model (DB)
The model or data base (DB) defines the server 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)
Updates the state of the Server DB.
cmd
is a 4 elements tuple, as follows:
{:rc, slave, address, count}
readcount
coils.{:ri, slave, address, count}
readcount
inputs.{:rhr, slave, address, count}
readcount
holding registers.{:rir, slave, address, count}
readcount
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.