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Programming Function Blocks and Features
Video Recorder – User Manual 109
Compare
Compare can be used instead of an Alarm’s output to control a relay. It can also provide on/off control
with hysteresis.
Compares 2 inputs. Call the result of this comparison “Result”. Result is a pulse that goes ON(1) when
comparison is true, and OFF(0) when comparison is not true. If hysteresis is given a value, then Result
will not go OFF(0) until hysteresis value is exceeded. Result is then processed according to the
specified condition type and condition time. The final output is a discrete pulse CVn OS.
COMPARE
OPERATOR
&
HYSTERESIS
Input #1
Input #2
Result
CONDITION
TYPE
&
CONDITION
TIME
CVn OS
Figure 4-2 Compare Signal Flow
Table 4-19 and Table 4-20 describe the Compare prompts. See Table 4-2 for additional prompts.
Table 4-19 Compare Prompts
Prompt Range/Selections Definition
INPUT #1
INPUT #2
OFF, analog parameter,
number
Input sources to be compared.
OPERATOR EQ, GT, LT, GTE, LTE, NEQ The Result will be set to ON(1) when the comparison is true:
Input #1 OPERATOR Input #2
where OPERATOR is:
EQ(=), GT(>), LT(<), GTE (≥), LTE (≤), NEQ(≠)
The Result will be set to OFF(0) when the comparison is false.
HYSTERESIS Number, OFF Applies to all operators except EQ and NEQ. If given a value,
hysteresis determines when Result goes OFF(0) after the
comparison becomes false.
Operator
Hysteresis Function
GT: Result goes OFF when Input #2 - Input #1 ≥ Hyst
GTE: Result goes OFF when Input #2 - Input #1 > Hyst
LT: Result goes OFF when Input #1 - Input #2 ≥ Hyst
LTE: Result goes OFF when Input #1 - Input #2 > Hyst
See Figure 4-3.
CONDITION TYPE NONE, DELAY, EXTEND,
PULSE, RT PULSE
See Table 4-20.
CONDITION TIME OFF or number Enter number of seconds of condition time. See Table 4-20.