org.lsst.ccs.drivers.modbus
Class Modbus

java.lang.Object
  org.lsst.ccs.drivers.modbus.Modbus

public class Modbus
extends Object

Handles Modbus RTU messages on a serial line

Author:

Owen Saxton

Constructor Summary

Modbus()

Method Summary

void	close() Closes the connection to the Modbus
org.lsst.ccs.drivers.ftdi.Ftdi	getFtdi() Gets the associated Ftdi object
void	open(int index, String serial) Opens a connection to the Modbus
void	open(String node, int index, String serial) Opens a connection to the Modbus
byte[]	readCoils(short dAddr, short cNmbr, short count) Reads a set of coils
byte[]	readDiscretes(short dAddr, short iNmbr, short count) Reads a set of discrete inputs
short[]	readInputs(short dAddr, short rNmbr, short count) Reads a set of input registers
short[]	readRegisters(short dAddr, short rNmbr, short count) Reads a set of holding registers
byte[]	send(short addr, byte[] cmnd, int timeout) Sends a command to a device on the Modbus and returns its response
void	writeCoil(short dAddr, short cNmbr, boolean value) Writes a coil
void	writeCoils(short dAddr, short cNmbr, short count, byte[] value) Writes a set of coils
void	writeRegister(short dAddr, short rNmbr, short value) Writes a holding register
void	writeRegisters(short dAddr, short rNmbr, short[] value) Writes a set of holding registers

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Modbus

public Modbus()

Method Detail

open

public void open(int index,
                 String serial)
          throws ModbusException

Opens a connection to the Modbus

Parameters:

index - The zero-based index of the Modbus adapter within the list of FTDI devices selected by the serial argument

serial - A string which, if non-null and non-empty, restricts the list of available devices to those with a serial number containing this string

Throws:

ModbusException

open

public void open(String node,
                 int index,
                 String serial)
          throws ModbusException

Opens a connection to the Modbus

Parameters:

node - The name of the node from which the Modbus is being served, or null for the local node

index - The zero-based index of the Modbus adapter within the list of FTDI devices selected by the serial argument

serial - A string which, if non-null and non-empty, restricts the list of available devices to those with a serial number containing this string

Throws:

ModbusException

close

public void close()
           throws ModbusException

Closes the connection to the Modbus

Throws:

ModbusException

getFtdi

public org.lsst.ccs.drivers.ftdi.Ftdi getFtdi()

Gets the associated Ftdi object

readCoils

public byte[] readCoils(short dAddr,
                        short cNmbr,
                        short count)
                 throws ModbusException

Reads a set of coils

Parameters:

dAddr - The Modbus address of the device

cNmbr - The number (starting at 1) of the first coil to read

count - The number of coils to read

Returns:

The array of read coil values, one per bit

Throws:

ModbusException

readDiscretes

public byte[] readDiscretes(short dAddr,
                            short iNmbr,
                            short count)
                     throws ModbusException

Reads a set of discrete inputs

Parameters:

dAddr - The Modbus address of the device

iNmbr - The number (starting at 1) of the first input to read

count - The number of inputs to read

Returns:

The array of read discrete values, one per bit

Throws:

ModbusException

readRegisters

public short[] readRegisters(short dAddr,
                             short rNmbr,
                             short count)
                      throws ModbusException

Reads a set of holding registers

Parameters:

dAddr - The Modbus address of the device

rNmbr - The number (starting at 1) of the first register to read

count - The number of registers to read

Returns:

The array of read register values

Throws:

ModbusException

readInputs

public short[] readInputs(short dAddr,
                          short rNmbr,
                          short count)
                   throws ModbusException

Reads a set of input registers

Parameters:

dAddr - The Modbus address of the device

rNmbr - The number (starting at 1) of the first register to read

count - The number of registers to read

Returns:

The array of read register values

Throws:

ModbusException

writeRegister

public void writeRegister(short dAddr,
                          short rNmbr,
                          short value)
                   throws ModbusException

Writes a holding register

Parameters:

dAddr - The Modbus address of the device

rNmbr - The number (starting at 1) of the register to write

value - The (16-bit) value to write

Throws:

ModbusException

writeCoil

public void writeCoil(short dAddr,
                      short cNmbr,
                      boolean value)
               throws ModbusException

Writes a coil

Parameters:

dAddr - The Modbus address of the device

cNmbr - The number (starting at 1) of the coil to write

value - The value (false = off, true = on) to write

Throws:

ModbusException

writeRegisters

public void writeRegisters(short dAddr,
                           short rNmbr,
                           short[] value)
                    throws ModbusException

Writes a set of holding registers

Parameters:

dAddr - The Modbus address of the device

rNmbr - The number (starting at 1) of the first register to write

value - The array of register values to write

Throws:

ModbusException

writeCoils

public void writeCoils(short dAddr,
                       short cNmbr,
                       short count,
                       byte[] value)
                throws ModbusException

Writes a set of coils

Parameters:

dAddr - The Modbus address of the device

cNmbr - The number (starting at 1) of the first coil to write

count - The number of coil values to write

value - The array of coil values to write

Throws:

ModbusException

send

public byte[] send(short addr,
                   byte[] cmnd,
                   int timeout)
            throws ModbusException

Sends a command to a device on the Modbus and returns its response

Parameters:

addr - The destination Modbus address

cmnd - The command byte array to send.

timeout - The timeout period (ms)

Returns:

The response byte array

Throws:

ModbusException