CAN bus

Dewesoft CAN Acquisition module is able to listen to the traffic on CAN bus interfaces from different manufacturers and acquire CAN messages, which is CAN Data Acquisition basic unit and can contain several signals -channels. Depending on the used CAN system, different car data is available like temperature, revolution, acceleration, and many more.

  • Required hardware - Dewesoft USB
  • Setup sample rate - At least 1 kHz

CAN messages/channels must be defined and set up with:

For additional help with CAN bus Acquisition visit Dewesoft PRO training -> Dewesoft Web page -> PRO Training.

When you select a CAN tab on Dewesoft Setup screen, on the upper part of screen CAN settings will appear:

  • CAN settings/options with information about CAN message / channel settings; to import data from DBC or ARXML file
  • Message/channel list with information about CAN messages / channels and primary SETUP column with Setup button to call CAN channel setup window

CAN_Menu

As a standard, there are no messages and channels available (report about the number of messages and channels in the list is displayed on the right part of this area). There are three ways to create them:

  • Import messages / channels from existing DBC or ARXML file
  • Add messages / channels manually
  • Use scan mode to find messages / channels automatically

All this work can be done with settings and options on this part of CAN Setup screen.

CAN settings / options

CAN port number

Before you add messages or channels, you have to select the CAN port. To select the port simply click on appropriate CAN tab.

CAN_SelectCh

Numbers of tabs depend on selected ports in CAN HW setup.

For further information about CAN visit  ->Dewesoft Web page  -> Support -> Downloads.

CAN speed - baud rate

The baud rate setting is very important. In fact, some vehicle operation can be interrupted if we connect to the bus with the wrong baud rate set.

Select the CAN speed from the kBaud field drop-down list or enter the value. Available are all common values from 5 to 1000 kBaud.

Dewesoft supports different CAN speeds for each CAN port. Under the baud rate edit box we have also a notification of how many messages came through the bus and how many of them were corrupted (red). This information shows if the baud rate is correct and also if the bus has any problems due to a bad connection or bus overload.

Import of messages and channels

You can import messages and channels from DBC and ARXML files or from XML and CAN setup files in Dewesoft specific format. ARXML version 3 and 4 are supported.

To import messages you should click on the import button in CAN setup.

When you click on the button the window to select the file to import will appear. If there were no previous existing messages you can just select the file and messages will be imported.

If there are already some existing messages the warning will show and you will have to choose if you want to delete or keep existing messages.

If you select to keep the existing messages you will have to choose how to merge messages with the same ArbID. You can select to not merge which will just add the channels to messages with same ArbId or you can merge them by channel name or channel bits.

Export of messages and channels

You can export messages and channels to DBC file or to XML file with Dewesoft specific format. Exporting to ARXML is not supported.

To export messages you should click on the export button.

When you click on the export button the window to select the file name and type will appear.

Searching for messages automatically

Use scan mode to find messages / channels automatically.

When you have already connected a CAN bus system to the Dewesoft system, you can also click the Scan check-box in the upper left corner.

CAN_Scan

As soon as we check the Scan option, the messages which are coming from the bus will be displayed. So now we can see message IDs, the speed of messages and raw binary values coming from the bus.

CAN_Scan_Results

The example above shows five new messages, which have been found automatically.

NOTE: The scan function can also only find messages; it is not able to identify the signals (channels) within the messages.

If we know, we can define the channels from the specification. We choose the Setup button and the empty message setup screen - Can channel setup window will appear (see below).

Selecting messages / channels

To select/deselect all message please click on the On/Off tab panel to get following options:

  • Select all - this will select all messages and channels which are expanded in the current view. If you want to select all channels from all messages, it is easiest to use channel view and then Select all. All messages will be enabled as soon as there is a channel within that message set to Used.
  • Deselect all - will set all channels to off
  • Remove all empty messages - will erase all messages without channels
  • Remove all unused messages - will erase all messages and channels within the messages which are set to off
  • Show all channels- toggle will display all channels
  • Show used channels - toggle will display only channels which are set to used

J1939 support

J1939 is used to enable special decoding of arbitration ID which includes the sender, receiver and the message ID itself. Arb ID is always extended in this case. This is most widely used on trucks. Please make sure that the bus type is really J1939 before enabling this option.