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 library
  • 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 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. Up to 4 CAN ports are supported by Dewesoft.

To select the port simply click on appropriate CAN button, select from CAN0 to CAN3 (depending on available ports).

CAN_SelectCh

Numbers of buttons 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 messages / channels from existing .dbc file

Press the DBC Library Import button to get a standard Open window. Now select the required *.dbc file  and press the Open button to import the desired file and a list of all available messages and channels will appear. 

(see also -> Messages/channel list)

You can edit the messages and channels manually.

Also export of CAN messages is possible. For that, please enable the Allow CAN export option in Dewesoft settings. The tuner can be found by opening System folder (go to Settings -> Advanced -> Hardware). The export can be enabled in the CAN section.

CAN_Allow-Export

After restart of Dewesoft, export DBC option is also available in CAN channel setup.

CAN_Import-Export

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.