6-2
CM35 Counter Module
(4) J31069-D0416-U001-A5-7618
6.1
Function Description
In this operating mode, the CM35 uses period duration measurement to ac-
quire small frequencies.
The CM35 measures the exact time between two falling edges of the count-
ing signal by counting the pulses of an internal precision-quartz reference
frequency. The period duration of the input signal is calculated from the
counting value after a period, divided by the reference frequency (in kHz).
Example:
-- Counting value = 100
-- Reference frequency = 100 kHz (standard value)
100
100 kHz
= 1 msec ( 1 kHz)
Þ
Period duration = 1 msec or frequency = 1 kHz
At a measuring value width of 16 bits and a reference frequency of 100 kHz,
period duration measurements between 655 msec (counting value 65500) and
1 msec (counting value 100) can be performed with a resolution of 1% with-
out switching the range.
Note
The resolution depends on the lower counting value (i.e., the minimum
period duration).
The reference frequency can be adjusted for measurement of longer period
durations. The following table shows the reference frequencies and the result-
ing measuring range.
Table 6-1
Measuring ranges
Counting
Range
Lower
Counting
Value
Upper
Counting
Value
Reference Frequency
Measuring Range
16 bits
100
65500
100 kHz
655 msec to 1 msec
(1.53 Hz to 1 kHz)
50 kHz
1,310 msec to 2 msec
(0.76 Hz to 500 Hz)
25 kHz
2,620 msec to 4 msec
(0.38 Hz to 250 Hz)
Measuring range
Period Duration Measurement Operating Mode
Summary of Contents for SIMATIC CM35
Page 1: ...SIMATIC Counter Module CM35 Manual Release 06 2000 ...
Page 9: ...vi CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Table of Contents ...
Page 10: ...1 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Product Overview 1 ...
Page 20: ...2 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Function Description 2 ...
Page 23: ...2 4 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Function Description ...
Page 47: ...3 24 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Commissioning ...
Page 48: ...4 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Data Communication with the CM35 4 ...
Page 70: ...5 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Pulse Counter Operating Mode 5 ...
Page 98: ...7 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Timer Operating Mode 7 ...
Page 112: ...8 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Positioning Operating mode 8 ...
Page 131: ...8 20 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Positioning Operating mode ...
Page 133: ...A 2 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Literature ...
Page 134: ...B 1 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 EC Declaration of Conformity B ...
Page 135: ...B 2 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 EC Declaration of Conformity ...
Page 141: ...Glossary 6 CM35 Counter Module 4 J31069 D0416 U001 A5 7618 Glossary ...