Siemens SIMATIC CM35, Manual

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5-5
CM35 Counter Module
(4) J31069-D0416-U001-A5-7618
When you specify the counting direction, you determine how the comparison
value/start value parameter will be used.
Counting up:
The transferred value is the comparison value.The following happens when a
counter is started.
-- Counting begins with the start value
²
0.
²
-- The counting value is incremented with each encoder pulse.
When the counting value reaches the specified comparison value, the para-
meterized reactions are triggered (e.g., reset digital output, trigger hardware
interrupt).
Counting down:
The transferred value is the start value. The following happens when a count-
ing procedure is started.
-- The counting value is set to the specified start value.
-- The counting value is decremented with each encoder pulse.
When the counting value reaches the comparison value ² 0, ² the parameter-
ized reactions are triggered (e.g., reset digital output, trigger hardware inter-
rupt).
The comparison value/start value can be specified for a specific channel.
Table 5-3 Comparison and start value
Variable:
Comparison or Start Value
(Depending on Direction of
Counting)
Parameter
Block
Offset Data
Type Value
Range
Cmp_Start_Value_Chan_1 1 2.0 Word 0 to 65535
Cmp_Start_Value_Chan_2 1 4.0 Word
Cmp_Start_Value_Chan_3 1 6.0 Word
Cmp_Start_Value_Chan_4 1 8.0 Word
Cmp_Start_Value_Chan_5 1 10.0 Word
Cmp_Start_Value_Chan_6 1 12.0 Word
Cmp_Start_Value_Chan_7 2 2.0 Word
Cmp_Start_Value_Chan_8 2 4.0 Word
Comparison value/
start value
Pulse Counter Operating Mode