Class ModbusServer

Namespace

Pamoja.Modbus

Assembly

Pamoja.Modbus.dll

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.

public sealed class ModbusServer : IDisposable

Inheritance

object

ModbusServer

Implements

IDisposable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Examples

using var meter = new ModbusServer(17);
meter.SetHoldingRegisters(107, [2301, 418, 0]);

Remarks

Answer(ReadOnlySpan<byte>) 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. A request the device cannot serve is answered with the exception the application protocol gives: an unknown function, then a quantity or value out of range, then an address the device does not have.

Put a device on a ModbusLine to poll it with a ModbusClient. The line shares the device, so this object still reads and changes its tables.

Constructors

ModbusServer(byte)

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

public ModbusServer(byte unit)

Parameters

unit byte

Its address, 1 to 247.

Exceptions

PamojaException

The unit is 0, the broadcast address, or 248 to 255, which the specification reserves.

Properties

Served

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

public int Served { get; }

Property Value

int

Unit

The device's unit address.

public byte Unit { get; }

Property Value

byte

Methods

Answer(ReadOnlySpan<byte>)

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

public byte[]? Answer(ReadOnlySpan<byte> frame)

Parameters

frame ReadOnlySpan<byte>

The frame as it came off the line, CRC included.

Returns

byte[]

The frame to send back, or null 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.

Coil(ushort)

Reads a coil.

public bool? Coil(ushort address)

Parameters

address ushort

The coil's address.

Returns

bool?

Its state, or null when the device has no coil there.

DiscreteInput(ushort)

Reads a discrete input.

public bool? DiscreteInput(ushort address)

Parameters

address ushort

The input's address.

Returns

bool?

Its state, or null when the device has no input there.

Dispose()

Releases this handle to the device. A line it is on keeps its own share.

public void Dispose()

HoldingRegister(ushort)

Reads a holding register.

public ushort? HoldingRegister(ushort address)

Parameters

address ushort

The register's address.

Returns

ushort?

Its value, or null when the device has no register there.

InputRegister(ushort)

Reads an input register.

public ushort? InputRegister(ushort address)

Parameters

address ushort

The register's address.

Returns

ushort?

Its value, or null when the device has no register there.

SetCoils(ushort, ReadOnlySpan<bool>)

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

public void SetCoils(ushort start, ReadOnlySpan<bool> values)

Parameters

start ushort

The first coil's address.

values ReadOnlySpan<bool>

Their states, in address order.

SetDiscreteInputs(ushort, ReadOnlySpan<bool>)

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

public void SetDiscreteInputs(ushort start, ReadOnlySpan<bool> values)

Parameters

start ushort

The first input's address.

values ReadOnlySpan<bool>

Their states, in address order.

SetHoldingRegisters(ushort, ReadOnlySpan<ushort>)

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

public void SetHoldingRegisters(ushort start, ReadOnlySpan<ushort> values)

Parameters

start ushort

The first register's address.

values ReadOnlySpan<ushort>

Their values, in address order.

SetInputRegisters(ushort, ReadOnlySpan<ushort>)

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

public void SetInputRegisters(ushort start, ReadOnlySpan<ushort> values)

Parameters

start ushort

The first register's address.

values ReadOnlySpan<ushort>

Their values, in address order.