Message Properties Dialog Box

To create a message, right-click CAN Channels in Data Neighborhood and select Create Message. Configure each property of a message using the information in the sections below. For information about changing properties for multiple messages at once, refer to Changing Properties of Multiple Messages or Channels.

Name

The message name can contain up to 64 characters. The message names must be unique in MAX. The message name must not contain a colon (:), period (.), or comma (,).

Arbitration ID

The arbitration ID is the identifier for the CAN message. The standard format contains 11 bits, the extended format 29 bits. You can display the arbitration ID in hexadecimal or decimal by right-clicking on CAN Channels and selecting Options. In hexadecimal mode, the display has a 0x prefix, but it is not necessary to enter this prefix before the ID.

J1939

The J1939 button is only enabled when selecting Extended Frame Format. MAX provides a dialog for editing Extended CAN IDs conforming to the J1939 standard.

Data Bytes

Number of data bytes in the message. A message can contain 1 to 8 data bytes.

Interface

Default interface to be used for this message. If the interface is not provided to the Channel API Initialize function, this default interface is used. If the interface is ANY in MAX, it implies that no interface has been assigned and an interface must be provided to the Initialize function.

Message Channels

The message channel list contains the names of all channels associated with this message. You can add a channel to the message by clicking the Add button or change the properties of an existing channel by clicking the Edit button.

Note  When you are creating a message using the Create Message menu selection, you cannot add channels to the message using the Add button, as the message does not exist yet. After the message is created, you can add channels by right-clicking on the message, selecting Properties, and using the Add option to add the desired channels.

Message Overview

The message overview window displays the message with all contained channels graphically. The vertical axis describes the byte number, starting with 0 for the first byte. The horizontal axis describes the bit number of the byte starting with 0 for the least significant bit in the byte. Bytes not available in the message are dimmed.

A channel can start in any valid bit of the message. The channel bits are numbered beginning with 0 for the least significant bit.

The channels are shown in the Message Overview using alternating colors.

Clicking on any bit in a channel highlights the channel and selects the channel name in the list box. Clicking again outside of any channel returns to the alternating colors view.

Overlapping bits of two channels are highlighted by red crosses. A red indicator above the message overview indicates an error condition. An error also occurs when the channel bits exceed the 64-bit range of a message. In such an event, the bits are not displayed, but you can recognize the error condition by the red indicator.

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