Safety Considerations Guide, Tricon v9.0 - Tuv-fs.com

68 Alarm UsageAlarm UsageTo implement the guidelines, the alarms described below are provided withTriStation 1131 Developer’s Workbench.Programming Permitted AlarmTo remind the operator to lock out programming changes after a download change,or for applications in which download changes are prohibited, connect theALARM_KEYINPROGRAM output to an alarm.Remote Access AlarmIn applications for which remote changes are not allowed, connect theALARM_KEYINREMOTE output to an alarm.Response Time and Scan TimeResponse time refers to the maximum time allocated for the controller to detect achange on an input point and to change the state of an output point. Response timeis primarily determined by scan time (the rate at which the program is run), but isalso affected by process time (how fast the process can react to a change). Theresponse time of the controller must be equal to or faster than the process time. Thescan time must be at least two times faster than the response time. To meet therequired response time of the process, set the MAX_SCAN_TIME input to lessthan 50% of the required response time. When the actual scan time as measured bythe firmware exceeds the MAX_SCAN_TIME value, theALARM_RESPONSE_TIME output becomes true.Disabled Points AlarmA project should not contain disabled points unless there is a specific reason fordisabling them, such as initial testing. An alarm is available to alert the operationthat a point is disabled.Tricon Safety Considerations Guide