Period Measurement - Siemens SIMATIC ET 200S Operating Instructions Manual

3.7.7

Period Measurement

Definition
In period measurement mode, the 1Count5V/500kHz measures the time between two
positive edges of the counting signal by counting the pulses of an internal quartz-accurate
reference frequency (16 MHz) within a set integration time.
Integration Time
You preset the integration time with the Integration Time parameter (see the table below).
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.
Period Measurement
The value of the calculated period is given in the unit 1 µs and 1/16 µs. The measured period
can be read in the feedback interface (byte 0 to 3).
Figure 3-28
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
Integration time
Any T n x 10 ms
DP
T < 10 ms n x T
DP
T ≥ 10 ms n x T
DP
Period Measurement with Gate Function
Range of n
n
min
1
10 ms/T [ms] +1
DP DP
1
DP
are omitted.
DP
1Count5V/500kHz
3.7 Measurement Modes
n
max
12000
12000
1
120 000 ms/T
DP
[ms]
1
177