Parameterising 2/4xcounter module
Measuring the period (modes 17 and 19)
12
Parameter setting
12.4
12.4.10
l
12.4-26
EDSPM-TXXX-3.0-04/2004
12.4.10 Measuring the period (modes 17 and 19)
1
2
3
4
5
6
7
8
9
10 GND
+24VDC
In1 (RES)
In2 (CLK)
In3 (START)
Out0
In4 (STOP)
n.c.
n.c.
Out1
epm-t087
Fig. 12.4-33 Terminal assignment of the 2/4xcounter in the modes 17 and 19
Modes 17 and 19 allow the determination of the average period of ”n” measured
period of signal at input IN2 (CLK).
The modes differ in triggering the output Out0 / Out 1 differently.
Note!
For measuring the frequency of the period, the counters 0 and 1
are required. For this, both counters must be parameterised to
mode 17 or 19. Different modes cannot be set.
With the PDO byte 7 (Data In)a reference frequency (f
ref
) is transmitted to counter
1(seefigure”counter access”). The number ”m” of the reference frequency pulses
determines the gate time (period of time the counter 1 is to be released). ”m” can
be between 1 and 2
32
-1 and is loaded into the compare register.
A LOW-HIGH edge at input IN1 (RES) sets the counter to zero.
A LOW-HIGH edge at input IN3 (START) starts the measuring process.
During the measuring process the counter 1 counts with the first LOW-HIGH edge
at the input IN2 (CLK) the pulses ”m” of the reference frequency. Simultaneously
the counter 0 counts every LOW-HIGH edge at the input IN2 (CLK).
Both counters are stopped when
z
the counter 0 reaches the Compare value, or
z
input IN4 (STOP) receives a HIGH signal.
Terminal assignment
RES signal
START signal
CLK signal
STOP signal
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