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Operating Modes, parameters and commands
7.4 Measuring modes
FM 350-1 Counter module
140
Manual, 05/2011, A5E03648639-01
7.4.3
Frequency measuring
Frequency Measurement
In the frequency measurement operating mode, the FM 350-1 counts the pulses that occur
within a dynamic measuring time.
The value of the calculated frequency is made available in the unit 10
-3
Hz. You can read the
measured frequency value at the feedback interface (Bytes 0 to 3).
8SGDWHWLPH
8SGDWHWLPH
&RXQWSXOVHV
,QWHUQDOJDWH
6WDUWRIIUHTXHQF\
PHDVXUHPHQW
(QGRIIUHTXHQF\
PHDVXUHPHQW
Figure 7-32 Frequency Measurement With Gate Function
Update Time
The FM 350-1 updates the measured values cyclically. You specify the update time with the
"Update time" parameter. You can change the update time during operation.
Table 7- 32 Calculating the Update Time
Value range of n
Boundary conditions
Update time
n
min
n
max
Non-isochronous mode
Any T
DP
n × 10 ms
1
1000
T
DP
< 10 ms
n × T
DP
(10 ms/T
DP
[ms] ) +1
1)
1000
Isochronous mode
T
DP
≥ 10 ms
n × T
DP
1
10000 ms/T
DP
[ms]
1)
1
The decimal places obtained after division by T
DP
are omitted.
It is prohibited to exceed these limits. If these limits are exceeded, the FM 350-1 generates a parameterization error and
does not switch to isochronous mode.
Summary of Contents for SIMATIC S7-300 FM 350-1
Page 8: ...Table of contents FM 350 1 Counter module 8 Manual 05 2011 A5E03648639 01 ...
Page 186: ...Technical data 11 2 Technical data FM 350 1 Counter module 186 Manual 05 2011 A5E03648639 01 ...
Page 188: ...Replacement parts FM 350 1 Counter module 188 Manual 05 2011 A5E03648639 01 ...
Page 190: ...References FM 350 1 Counter module 190 Manual 05 2011 A5E03648639 01 ...
Page 194: ...Glossary FM 350 1 Counter module 194 Manual 05 2011 A5E03648639 01 ...