gefran 850 Installation And Instruction Manual page 202

Symmetrical deviation alarm
A single alarm setpoint AL1 and a single hysteresis value
Hyst1 are set.
When a direct alarm is set, the alarm trips when the measured
value is less than SP - AL1 or greater than SP + AL1.
When an inverse alarm is set, the alarm trips when the
measured value is between SP - AL1 and SP + AL2
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Symmetrical deviation alarm
SP+AL1
SP
SP -AL1
inverse
direct
Hyst1
Hyst1
tempo