Continuous Frequency Measurement - Siemens SIMATIC ET 200S Operating Instructions Manual

3.7.4

Continuous Frequency Measurement

Definition
In frequency measurement mode, the 1Count5V/500kHz counts the pulses that arrive within
a dynamic measuring time.
Update time
The 1Count5V/500kHz updates the measured values cyclically. You preset the update time
with the Update Time parameter (see table). You can change the update time during
operation.
Table 3-11 Calculation of the Update Time
Boundary conditions
Non-isochrone mode
Isochrone mode
Any digits after the decimal point that come about after dividing by T
1
These limits must not be violated. If these limits are violated, the 1Count5V/500kHz generates a parameter assignment
error and will not go into isochrone mode.
Frequency Measurement
The value of the calculated frequency is made available in the unit Hz*10
frequency value can be read in the feedback interface (byte 0 to 3).
Figure 3-25
Limit-Value Monitoring
The following value ranges are permitted for limit-value monitoring:
Encoder type
5-V encoders
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
Update time
Any T n x 10 ms
DP
T < 10 ms n x T
DP
T ≥ 10 ms n x T
DP
Frequency Measurement with Gate Function
Range of n
n
min
1
(10 ms/T
DP DP
1
DP
are omitted.
DP
Low limit f
u
0 to 499,999,999 Hz*10
-3
1Count5V/500kHz
3.7 Measurement Modes
n
max
[ms]) +1
1
1000 ms/T
. The measured
-3
High limit f
o
f +1 to 500,000,000 Hz*10
u
1000
1000
[ms]
1
DP
-3
169