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ANALOG IN 15 BIT VOLTAGE/CURRENT 8CH IC220ALG221
Signal Scanning or Fast, Sudden Signals
The ANALOG IN 15 BIT VOLTAGE/CURRENT
8CH terminal is ideal for scanning signals. As a
result of the high input cut-off frequency
(3.5 kHz), there are no limiting elements in the
analog stage. The maximum signal frequency
that can be scanned depends on the firmware
runtime and the bus cycle time.
The terminal measuring device can measure si-
gnals with a frequency of 1/800 µs = 1.25 kHz.
According to Shannon's sampling theorem,
therefore, the signal frequency that can be scan-
ned is 1.25 kHz/2 = 0.625 kHz.
This signal frequency can only be achieved if
sufficiently fast bus operation can be ensured.
The following configurations and measures are
recommended:
–
Measured value acquisition: according to
standard method 1 or 2
–
Filtering: no mean-value generation
This increases the dynamic response of the
terminal.
–
Adjust the bus cycle time to the firmware
runtime
This achieves discrete periods of scanning.
Example: in standard method 1, the firm-
ware runtime is <800 µs, i.e., the bus cycle
time should be set to 800 µs.
38
Linked Voltages
When using linked voltages, ensure that the
ANALOG IN 15 BIT VOLTAGE/CURRENT 8CH
terminal has eight single-ended inputs. A com-
mon ground potential should be used with linked
voltages. As the terminal has many measuring
ranges, for example the 0 V to 50 V range, and
the resolution is high enough, applications with
several linked voltages can also be used without
any problems.
Figure 12 Measuring linked voltages
6226B_GE
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