Issue
Performance of the Netcontroller could be slow because of the scan rate
Environment
All Netcontrollers
Cause
Programs and functions that are polling data frequently can drive up the scan time
Resolution
The scan cycle has the following components to evaluate and process: System variables, download schedules, update inputs, run programs, update outputs, process alarms. Any of these can drive up the scan, but typically there is a program that is requesting polling updates on child controllers (infinet, mstp, modbus) that is driving up the scan. To troubleshoot this, disable all of the programs and enable them one by one to determine which programs are driving up the scan. Once that is determined, focus on adjusting the program accordingly.
Performance of the system can be affected by a slow scan time and normally as the scan rate goes up, the performance goes down.
An extremely high scan rate would be 50 where the performance is unusable, but could still be working.
A scan rate of less than 1 second is ideal, but the real measure of the acceptable rate would be determined by the end user. A scan time of 5 seconds may be acceptable.
The scan rate is similar to CPU utilization on a PC, so that high utilization over long periods of time will be more taxing on the controller.
