Troubleshooting a potential problem with a ControlLogix® device may involve many factors including but not limited to configuration or communication path issues. The more information provided up front during the support process will speed up the research portion considerably. Review the General Troubleshooting page for basic tips and getting help.
More information does not hurt when it comes to debugging issues via logs. Often, logs are the only way to debug a problem.
Additional logging options may be needed for such issues related to OPC items or socket connection information.