Diagnostic log files

The diagnostic log files contain status information, warnings, error messages, and debugging messages. They offer information on the firmware start-up and operation of a controller of the PLCnext family. It is a good compromise between information and system performance.
You will find the files in the /opt/plcnext/logs folder on the file system of your controller. The file system can be accessed via the SFTP protocol. The SFTP client software is required for this (e.g., WinSCP). Further information can be found in the topic  Connecting to the controller.

The diagnostic log files contain the following message types:

• Error & Fatal: If messages of the Error or Fatal type are issued, the controller is stopped. The errors mainly arise during startup, or during execution of a user program.
• Warning: Messages of type Warning indicate potentially occurring errors.
• Information: The core components issue messages of the Information type. These provide an overview of the system status.

Example of an Output.log diagnostic log file:Click to show an example of an Output.log diagnostic log file

In the following sections you will find descriptions on the log files from firmware version 2025.0, up to firmware version 2024.6 and a description on the enhanced debug log.

Log files up to firmware version 2024.6

Up to firmware version 2024.6, there is one log file for all components of the firmware. The Output.log diagnostic log file contains status information, warnings, error messages, and debugging messages. You will find the file in the /opt/plcnext/logs folder on the file system of your controller. The diagnostic log file Output.log is configured as a rolling file in the configuration file /etc/plcnext/Device.log.ini. If the file is > 16 MB, old log messages are stored in a separate file. These separate files are created with an index starting from 1, e.g. /opt/plcnext/logs/Output.log.1. Every file with an index can be copied for evaluation.

Enhanced Debug Log

Note: Activate the enhanced PLCnext Debug Log mode only if you are requested to do so by the support.

For a deeper insight into the system, it is possible to activate an extended log mode. In addition to the messages of typeError,  Warning, and Information, this also displays the developmentDebug messages. To activate the extended mode, change the configuration of the /etc/plcnext/Device.log.ini (e.g. /etc/plcnext/AXCF2152.log.ini) as follows.

Note: The enhanced logging generates a higher system load that might influence the timing of running applications.
Phoenix Contact strongly recommends to deactivate the enhanced logging after usage.

Preconditions: 

For the modification of the *.log.ini (e.g. AXCF2152.log.ini) a root user is necessary. How to create a root user can be read here. Be sure to observe all warnings.

• Open the configuration file *.log.ini (e.g. AXCF2152.log.ini) on the file system of your controller under \etc\plcnext.
• Change the threshold key from INFO to  DEBUG as in the following example:

log4cplus.rootLogger=DEBUG, ConsoleAppender1, RollingFileAppender1, SysLogAppender1

#SysLogAppender1:
log4cplus.appender.SysLogAppender1=log4cplus::AsyncAppender
log4cplus.appender.SysLogAppender1.Appender=log4cplus::SysLogAppender
log4cplus.appender.SysLogAppender1.Appender.layout=log4cplus::PatternLayout
log4cplus.appender.SysLogAppender1.Appender.layout.ConversionPattern=%c %p - %m%n
log4cplus.appender.SysLogAppender1.Appender.Threshold=INFO

#ConsoleAppender1:
log4cplus.appender.ConsoleAppender1=log4cplus::AsyncAppender
log4cplus.appender.ConsoleAppender1.Appender=log4cplus::ConsoleAppender
log4cplus.appender.ConsoleAppender1.Appender.layout=log4cplus::PatternLayout
log4cplus.appender.ConsoleAppender1.Appender.layout.ConversionPattern=%d{%d.%m.%y %H:%M:%S.%q} %-30.30c %-5p - %m%n
log4cplus.appender.ConsoleAppender1.Appender.Threshold=INFO

#RollingFileAppender1
log4cplus.appender.RollingFileAppender1=log4cplus::AsyncAppender
log4cplus.appender.RollingFileAppender1.Appender=log4cplus::RollingFileAppender
log4cplus.appender.RollingFileAppender1.Appender.File=/opt/plcnext/logs/Output.log
log4cplus.appender.RollingFileAppender1.Appender.CreateDirs=true
log4cplus.appender.RollingFileAppender1.Appender.MaxFileSize=16MB
log4cplus.appender.RollingFileAppender1.Appender.MaxBackupIndex=1
log4cplus.appender.RollingFileAppender1.Appender.layout=log4cplus::PatternLayout
log4cplus.appender.RollingFileAppender1.Appender.layout.ConversionPattern=%d{%d.%m.%y %H:%M:%S.%q} %-60c %-5p - %m%n
log4cplus.appender.RollingFileAppender1.Appender.Threshold=DEBUG

• After you have changed the configuration file, save the changes and reboot the controller.

The enhanced logging is now active and the message type DEBUG is now available in the Output.log file as in the following example:

• After all necessary logs have been collected, the changed logging configuration has to be reverted.
  Recommended: Remove the file /media/rfs/rw/upperdir/etc/plcnext/Device.log.ini and reboot the PLC. 
  ↪ This procedure ensures that no Device.log.ini persists in the overlay file system which may cause problems when the firmware is later upgraded or downgraded.

Template Loggable

You can apply tags to log messages from components, programs or other code elements. See  Common classes for more information.