net.solarnetwork.io.modbus

Interface ModbusMessage

All Known Subinterfaces:

AddressedModbusMessage, BitsModbusMessage, MaskWriteRegisterModbusMessage, ModbusMessageReply, ReadWriteRegistersModbusMessage, RegistersModbusMessage

public interface ModbusMessage

API for a Modbus message.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)
ModbusError	getError()	Get the Modbus error code.
ModbusFunction	getFunction()	Get the Modbus function code.
int	getUnitId()	Get the device unit ID.
int	hashCode()
default boolean	isException()	Test if this message is an exception (error).
boolean	isSameAs(ModbusMessage obj)	Compare the "sameness" of this message to another.
<T extends ModbusMessage> T	unwrap(Class<T> msgType)	Unwrap this message as a specific message type, if possible.
default ModbusMessage	validate()	Validate this message in some way.

Method Detail

getUnitId

int getUnitId()

Get the device unit ID.

Modbus allows only values from 0-255 for the unit ID.

Returns:

the unit ID, as an integer

getFunction

ModbusFunction getFunction()

Get the Modbus function code.

Returns:

the function code, never null

getError

ModbusError getError()

Get the Modbus error code.

Returns:

the error code, or null if not an error

isException

default boolean isException()

Test if this message is an exception (error).

Returns:

true if getError() it not null

unwrap

<T extends ModbusMessage> T unwrap(Class<T> msgType)

Unwrap this message as a specific message type, if possible.

This method should be used instead of relying on a direct instanceof operator, because the actual Modbus message may be encapsulated in some way. For example, instead of trying this:

 
 // WRONG WAY: DO NOT TRY THIS
 ModbusMessage msg = getMessageFromSomewhere();
 if ( msg instanceof RegistersModbusMessage ) {
   RegistersModbusMessage r = (RegistersModbusMessage)msg;
   // do something with registers...
 }
 
 

try this instead:

 
 ModbusMessage msg = getMessageFromSomewhere();
 RegistersModbusMessage r = msg.unwrap(RegistersModbusMessage.class);
 if ( r != null ) {
   // do something with registers...
 }
 
 

Type Parameters:

T - the message type to unwrap

Parameters:

msgType - the class to unwrap as

Returns:

the message as the given type, or null if this message is not compatible with msgType

isSameAs

boolean isSameAs(ModbusMessage obj)

Compare the "sameness" of this message to another.

Parameters:

obj - the message to compare to this message

Returns:

if the class of other is the same as this class, and the properties are the same

validate

default ModbusMessage validate()
                        throws ModbusValidationException

Validate this message in some way.

This method might validate a checksum or the overall structure of the message for correctness, throwing an exception if any validation fails.

Returns:

this message

Throws:

ModbusValidationException - if any validation failure occurs

hashCode

int hashCode()

Overrides:

hashCode in class Object

equals

boolean equals(Object obj)

Overrides:

equals in class Object