CANtrace supports the playback of existing log files in the Vector ASCII (ASC) format. Playback can be configured in one of three ways:

• Determined by the Log File: Normal playback.
• 0 – Display Only: Playback to channel zero.
• N – CAN Bus: Playback to physical CAN bus, where the channel number (N) ranges from 1 to 9.

The first message in the log file is played back immediately, regardless of its timestamp. CANtrace supports any Vector ASCII (ASC) log file, whether generated by CANtrace, a hardware CAN logger or a third-party tool. If a log file is not in the Vector ASCII format, an error message will be displayed.

Playback Channel
Selects the software channel to which the messages in the log file are sent.

1. Determined by the Log File
   
   • Used for normal internal playback, displaying messages from the log file in the Trace, Data, and Graph tabs as if they were coming from a real CAN bus.
   • Playback starts when going “on bus” and continues until the log file reaches its end, at which point CANtrace automatically goes off bus.
   • Messages retain their original channel numbers as recorded in the log file.
   • During playback, no real CAN messages are received or transmitted from the CAN network.
2. Channel zero
   • Used for internal playback, displaying messages from the log file in the Trace, Data, and Graph tabs as if they were coming from a real CAN bus.
   • Playback starts when going “on bus” and continues until the end of the log file, at which point CANtrace automatically goes off bus.
   • Regardless of the original channel, all messages appear as originating from playback channel 0.
   • During playback, real CAN messages are received or transmitted from the CAN network.
3. Channel 1 to 9
   • Messages from the log file are transmitted to a configured CAN channel at the specified rate.
   • Playback starts when going “on bus” and continues until the log file reaches its end.
   • CANtrace remains “on bus” after playback is complete.
   • All messages, regardless of their original channel, are sent to the selected CAN bus.

Note: When sending messages to the CAN bus, timing accuracy is only as good as the Windows timers used. As Windows is not a real-time operating system, a message may occasionally be sent as much as 100ms later than what the timestamp in the logfile would indicate. Messages are always sent in the correct order though.

Figure 9.1 Play Log File Settings

0 Play log file
Select this software channel to play back an existing log file.

Activate this channel
This setting is disabled unless a log file is specified in the Log File Name and Path section.

Activates log file playback.

Unless a physical CAN channel is selected as Playback Channel, ticking this box will prompt the user to deactivate all other channels.

If “0 – Display” is selected as Playback Channel, deactivating all other channels will prevent live CAN bus data from mixing with log file data during playback.

If “Determined by the Log File” is selected as Playback Channel, deactivating all other channels will have no effect on the playback, since live CAN bus data is ignored by default.

Playback Channel
This drop-down menu allows you to select the software channel for log playback.

• By default, “Determined by the Log File” is selected, meaning playback occurs internally.
• If “0 – Display only” is selected, playback occurs internally.
• If the channel amount selector is set to a value greater than 1, additional options (e.g “1 – CAN bus”, “2 – CAN bus”, etc.) will appear. Selecting one of these options directs playback to the corresponding CAN bus.

Important: A CAN interface hardware channel must be assigned to the selected software channel for playback to function correctly.

Log file name and path
To select a log file for playback, click the Browse button. This will open a file selection dialog that, by default, displays only files with compatible extensions (ASC and TXT). You can modify the filter setting to display all file types if needed. The selected filter preference is saved when opening a log file and will be applied the next time the dialog is opened.

Log Playback Rate
There are two playback rate options :

• As fast as possible (default): Plays back the log file messages at the maximum possible speed. This option is ideal for quickly processing a lengthy log, such as when generating a graph.
• At the rate recorded: Plays back the messages at the same speed they were originally recorded, ensuring a real-time replication of the logged events.

Once the desired playback settings are configured, click the Close button to exit the CAN Interfaces Settings dialog.