Omega Engineering OMB-CHARTSCAN 1400, User Manual

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Appendix B Configuration Aspects for Programmers
ChartScan User’s Manual B-27
As mentioned before, more than one channel can be assigned to any given output bit. For example, if the
following statement were appended to the above example, then either channel 2 or channel 3 will set digital
output #2.
PRINT#1,“OUTPUT07:A3,2X” ‘Assign alarm channel 3 to digital output 2
To disable a channel from an alarm, assign the channel to the null or “0" output:
PRINT#1,“OUTPUT07:A3,0X” ‘Disable channel 3 from digital output 2
Alarms and Set Points
Set Point Hysteresis
To avoid threshold transition problems, a hysteresis value can also be programmed. After the alarm set point is
exceeded, the signal must drop below the high set point, or above the low set point by the hysteresis value
before the alarm is reset. For example, assume a channel has alarm set points of 100 and -100, and a hysteresis
of 10. In this case, ChartScan would remain in an alarm condition until the set point fell below 90 or rose above
-90 depending on which of the two set points triggered the alarm.
Relationship Between Alarm Set Point, Hysteresis, and Unwanted Transitions