Modbux v0.3.9 Modbux.Rtu.Master View Source
API for a Modbus RTU Master device.
Link to this section Summary
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.
Link to this section Functions
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
orfalse
) specifies whether data is received as messages (mailbox) or by callingrequest/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 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
.
Open the Master serial port.
Read and parse the last request (if the last request timeouts).
Send a request to Modbus RTU Slave.
cmd
is one of:
{: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.
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
orfalse
) specifies whether data is received as messages (mailbox) or by callingrequest/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.