Technology modules
D300529 0115 - BL67 I/O modules12-66
12.5.3 Measurement mode
General
The measurement operation has not to be
started. It is done automatically, at the same time as the
counting operation. Depending on the parameterization (parameter byte 3, bit 5, Measurement mode),
either a frequency or a period duration count is executed.
Exception:
If, for the synchronization of the module, the parameter Synchronization with Z is set to p
eriodical, then
the parameter Measurement mode has to be set to frequency measur
ement in order to activate fre-
quency measurement.
The measuring operation is started by setting the inte
rnal software release signal, or by setting the
hardware and software release signal if the digital input is configured
as a hardware release.
Frequency measurement
Definition
In this operating mode the module counts the pulses received within a specified integra
tion time.
The integration time can be set by using
the register communication via register no. 60 REG_MEA-
SURE_TIME. It can be set in steps of 10 ms to between 10 ms and (2
32
-1) × 10 ms.
Prerequisites
Parameter Measurement mode = 0
Register no. 52 REG_SCALE_MUL = 1
Register no. 56 REG_SCALE_DIV = 1
Register no. 60 REG_MEASURE_TIME → integration time depending on
the application
The value of the determined frequency is displayed as a 10
-3
Hz value.
The measured frequency value can be read out from register no. 48 REG_MEASURED_ VALUE and, if
parameterized, from the Process input/status interface (bytes 8 to 11)
NOTE
.
The displayed value cannot be upda
ted until the integration time has elapsed.
Figure 12-34:
n*10 ms n*10 ms
integration time
count
pulses
internal
release
start of
frequency measurement
end of
frequency measuremen
The value displayed in bytes 8 to 11 of the feedback interface (process output) is defined via
parameter REG_AUX_ADR (parameter byte 14).
Here, enter the register no. of the value to be monitored (see Register bank of the module,
page 12-92).
Frequency mea-
surement with
release function
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