The controller Also known as remote terminal unit, RTU. A generic term for a device that is used to control and monitor one or more processes in field equipment. The most common control and monitoring device in an access control and security system is an access control panel. Other devices include security monitoring panels, elevator controllers, and fire monitoring devices. Controllers include programmable logic controllers (PLCs), loop controllers, bar code readers, and scientific analyzers. See also: C200 controller, control processor, CPM, hybrid controller, network node controller, PLC. performs a history backfill and there are trend A display in which changes in value over time of one or more point parameters are presented in a graphical manner. See also: display, point parameter. gaps/missed samples even though there has been no problem with the controller.
Using the HC Historian application, ensure that the controller has missed the specified samples.
A possible cause could be that the controller time is being changed or is being synchronized from another time source and the time has been moved forward.
Ensure only one server The computer on which the Experion database software and server utilities run. See also: Experion server TPS. is connected to this controller. Also ensure that an engineering tool, such as HC (Hybrid Control) Designer, has not changed the controller time.
In HC Designer, if points are configured with Use Signal Tag in the Trend Backfill Log Point Selection, the backfill data cannot be matched to points built in Experion. This results in bad address log messages when backfill is running. For more information, see the HC900 Hybrid controller. section in "Troubleshooting problems with specific controller models."