Struct Server 

pub struct Server { /* private fields */ }

A Modbus device: a unit address and the four tables it serves, coils, discrete inputs, holding registers, and input registers, each holding only the addresses it was given.

answer takes one RTU frame and returns the frame the device sends back, following the Modbus over Serial Line specification: a frame that fails its CRC, is for another unit, or is a broadcast gets no answer, and a broadcast write is still carried out. serve is the same at the PDU level, for a transport with its own framing. A request the device cannot serve is answered with the exception the application protocol’s state diagrams give: an unknown function, a quantity or value out of range, then an address the device does not have.

Examples

use pamoja_modbus::{Adu, Pdu, Server};

// A meter at unit 17 holding voltage, current, and a fault word from register 107.
let mut meter = Server::new(17)?.with_holding_registers(107, &[2301, 418, 0]);

let request = Pdu::read_holding_registers(107, 3).to_adu(17);
let reply = meter.answer(request.as_bytes()).expect("the meter answers its own unit");
let registers: Vec<u16> = reply.response().registers()?.collect();
assert_eq!(registers, [2301, 418, 0]);

// Register 110 is not in its table.
let past = Pdu::read_holding_registers(108, 3).to_adu(17);
let refused = meter.answer(past.as_bytes()).expect("an exception is an answer");
assert_eq!(refused.exception(), Some(pamoja_modbus::Exception::IllegalDataAddress));

Implementations

impl Server

pub fn new(unit: u8) -> Result<Server, ModbusError>

Makes a device at a unit address, with every table empty.

Arguments

• unit - its address, 1 to 247.

Returns

The device.

Errors

ModbusError::UnitOutOfRange for 0, the broadcast address, or 248 to 255, which the specification reserves.

pub fn with_coils(self, start: u16, values: &[bool]) -> Server

Gives the device coils at consecutive addresses.

Arguments

• start - the first coil’s address.
• values - their states, in address order.

Returns

The device.

pub fn with_discrete_inputs(self, start: u16, values: &[bool]) -> Server

Gives the device discrete inputs at consecutive addresses.

Arguments

• start - the first input’s address.
• values - their states, in address order.

Returns

The device.

pub fn with_holding_registers(self, start: u16, values: &[u16]) -> Server

Gives the device holding registers at consecutive addresses.

Arguments

• start - the first register’s address.
• values - their values, in address order.

Returns

The device.

pub fn with_input_registers(self, start: u16, values: &[u16]) -> Server

Gives the device input registers at consecutive addresses.

Arguments

• start - the first register’s address.
• values - their values, in address order.

Returns

The device.

pub fn set_holding_registers(&mut self, start: u16, values: &[u16])

Sets holding registers from an address on, adding any the device did not have, as its own measurements change.

Arguments

• start - the first register’s address.
• values - their values, in address order.

pub fn set_input_registers(&mut self, start: u16, values: &[u16])

Sets input registers from an address on, adding any the device did not have.

Arguments

• start - the first register’s address.
• values - their values, in address order.

pub fn set_coils(&mut self, start: u16, values: &[bool])

Sets coils from an address on, adding any the device did not have.

Arguments

• start - the first coil’s address.
• values - their states, in address order.

pub fn set_discrete_inputs(&mut self, start: u16, values: &[bool])

Sets discrete inputs from an address on, adding any the device did not have.

Arguments

• start - the first input’s address.
• values - their states, in address order.

pub fn coil(&self, address: u16) -> Option<bool>

Returns a coil’s state, or None when the device has no coil there.

pub fn discrete_input(&self, address: u16) -> Option<bool>

Returns a discrete input’s state, or None when the device has no input there.

pub fn holding_register(&self, address: u16) -> Option<u16>

Returns a holding register’s value, or None when the device has no register there.

pub fn input_register(&self, address: u16) -> Option<u16>

Returns an input register’s value, or None when the device has no register there.

pub fn unit(&self) -> u8

Returns the device’s unit address.

pub fn served(&self) -> usize

Returns how many requests the device has carried out, broadcasts included and refusals not.

pub fn serve(&mut self, pdu: &[u8]) -> Pdu

Serves one request PDU.

Arguments

• pdu - the request: a function code followed by its data.

Returns

The reply PDU: the normal response, or the exception the request earned.

pub fn answer(&mut self, frame: &[u8]) -> Option<Adu>

Answers one RTU frame, as a device on the line does.

Arguments

• frame - the frame as it came off the line, CRC included.

Returns

The frame to send back, or None when the device stays silent: the frame failed its CRC, is for another unit, or is a broadcast, whose write the device still carries out.

Trait Implementations

impl Clone for Server

fn clone(&self) -> Server

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Server

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Server

impl PartialEq for Server

fn eq(&self, other: &Server) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Peer for Server

Available on crate feature port only.

A server on the far end of a simulated port answers each write as one frame.

fn receive(&mut self, bytes: &[u8]) -> Vec<u8>

Takes the bytes the port wrote and returns the bytes the device sends back.

impl StructuralPartialEq for Server