Package jmri.jmrix.can

Class CanMessage

java.lang.Object
jmri.jmrix.AbstractMessage
jmri.jmrix.AbstractMRMessage
jmri.jmrix.can.CanMessage
All Implemented Interfaces:
CanFrame, CanMutableFrame, Message
public class CanMessage extends AbstractMRMessage implements CanMutableFrame
Base class for messages in a CANbus based message/reply protocol.

It is expected that any CAN based system will be based upon basic CANbus concepts such as ID (standard or extended), Normal and RTR frames and a data field.

The _dataChars[] and _nDataChars members refer to the data field, not the entire message.

"header" refers to the full 11 or 29 bit header; which mode is separately set via the "extended" parameter

CBUS uses a 2-bit "Pri" field and 7-bit "ID" ("CAN ID") field, with separate accessors. CBUS ID is set as a layout connection preference and registered by the traffic controller.

  • Field Details

  • Constructor Details

    • CanMessage

      public CanMessage(int header)
      Create a new CanMessage with 8 data bytes
      Parameters:
      header - The CAN Frame header value

    • CanMessage

      public CanMessage(int numDataBytes, int header)
      Create a new CanMessage of given length
      Parameters:
      numDataBytes - number of CAN Frame data bytes, max 8
      header - The CAN Frame header value

    • CanMessage

      public CanMessage(int[] d, int header)
      Create a new CanMessage from an int array
      Parameters:
      d - array of CAN Frame data bytes, max 8
      header - The CAN Frame header value

    • CanMessage

      public CanMessage(byte[] d, int header)
      Create a new CanMessage from a byte array
      Parameters:
      d - array of CAN Frame data bytes, max 8
      header - The CAN Frame header value

    • CanMessage

      public CanMessage(@Nonnull CanMessage m)
      Create a new CanMessage from an existing CanMessage
      Parameters:
      m - The existing CanMessage

    • CanMessage

      public CanMessage(@Nonnull CanReply m)
      Create a new CanMessage from an existing CanReply
      Parameters:
      m - The existing CanReply

  • Method Details

    • setTranslated

      public void setTranslated(boolean translated)
      Tag whether translation is needed. a "native" message has been converted already.
      Parameters:
      translated - true or false to set flag as required

    • isTranslated

      public boolean isTranslated()
      Check if translation flag has been set.
      Returns:
      false by default

    • hashCode

      public int hashCode()
      Hash on the header
      Overrides:
      hashCode in class AbstractMessage
      Returns:
      hashcode from sum of elements.

    • equals

      public boolean equals(Object a)
      Note that a CanMessage and a CanReply can be tested for equality.
      Overrides:
      equals in class AbstractMessage
      Parameters:
      a - CanMessage or CanReply to test against

    • toString

      public String toString()
      This format matches CanReply
      Specified by:
      toString in interface Message
      Overrides:
      toString in class AbstractMRMessage

    • toMonitorString

      public String toMonitorString()
      This format matches CanReply
      Specified by:
      toMonitorString in interface Message
      Returns:
      a human-readable representation of the message.

    • replyExpected

      public boolean replyExpected()
      Is a reply expected to this message?

      By default, a reply is expected to every message; either a reply or a timeout is needed before the next message can be sent.

      If this returns false, the transmit queue will immediately go on to transmit the next message (if any).

      Overrides:
      replyExpected in class AbstractMRMessage
      Returns:
      always false

    • getNumDataElements

      public int getNumDataElements()
      Get the number of data elements in a Message.
      Specified by:
      getNumDataElements in interface CanFrame
      Specified by:
      getNumDataElements in interface Message
      Overrides:
      getNumDataElements in class AbstractMessage
      Returns:
      number elements.

    • setNumDataElements

      public final void setNumDataElements(int n)
      Set the number of data elements in the main CAN Frame body.
      Specified by:
      setNumDataElements in interface CanMutableFrame
      Parameters:
      n - true number of data bytes, 0-8

    • getElement

      public int getElement(int n)
      Get a particular element in a Message.
      Specified by:
      getElement in interface CanFrame
      Specified by:
      getElement in interface Message
      Overrides:
      getElement in class AbstractMessage
      Parameters:
      n - Element Index.
      Returns:
      single element of message.

    • setElement

      public void setElement(int n, int v)
      Set a single Data Element at a particular index.
      Specified by:
      setElement in interface CanMutableFrame
      Specified by:
      setElement in interface Message
      Overrides:
      setElement in class AbstractMessage
      Parameters:
      n - index of element.
      v - value of element.

    • getData

      public int[] getData()
      Get the data bytes in array form.
      Returns:
      the actual int array

    • getHeader

      public int getHeader()
      Get the CAN Frame header.
      Specified by:
      getHeader in interface CanFrame
      Returns:
      header value

    • setHeader

      public void setHeader(int h)
      Set the CAN Frame header.
      Specified by:
      setHeader in interface CanMutableFrame
      Parameters:
      h - new header value

    • isExtended

      public boolean isExtended()
      Get if the CAN Frame has an extended header.
      Specified by:
      isExtended in interface CanFrame
      Returns:
      true if extended, else false

    • setExtended

      public void setExtended(boolean b)
      Set if the CAN Frame header is extended.
      Specified by:
      setExtended in interface CanMutableFrame
      Parameters:
      b - true if extended, else false

    • isRtr

      public boolean isRtr()
      Get if the CAN Frame is an RTR Frame.
      Specified by:
      isRtr in interface CanFrame
      Returns:
      true if RTR, else false

    • setRtr

      public void setRtr(boolean b)
      Set if the CAN Frame is an RTR Frame.
      Specified by:
      setRtr in interface CanMutableFrame
      Parameters:
      b - true if RTR, else false