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Application Notes
Notes on typical applications are provided here
in order to facilitate optimal use of the ANALOG
IN 15 BIT VOLTAGE/CURRENT 8CH terminal
in different operating modes.
Precision DC Measurements
Precision DC measurements constitute an opti-
mal area of application for the ANALOG IN 15
BIT VOLTAGE/CURRENT 8CH terminal. The
high-resolution analog-to-digital converter and
excellent instrumentation amplifier technology
achieve a very high level of accuracy (typically
0.02% in the voltage range).
In order to take full advantage of these features,
the following configurations are recommended:
–
Measured value acquisition: according to
standard method 1 or 2
–
Format: IB IL (high-resolution)
–
Filtering: 32-sample average
This suppresses undesirable interference sig-
nals and provides a low-noise, accurate measu-
red result. Non-time-critical, i.e., slow, proces-
ses are a prerequisite for this configuration.
6226B_GE
ANALOG IN 15 BIT VOLTAGE/CURRENT 8CH IC220ALG221
Closed-Loop Control Tasks
The ANALOG IN 15 BIT VOLTAGE/CURRENT
8CH terminal makes closed-loop control tasks
particularly easy to carry out. The terminal sup-
ports the advantages of bus with regard to time
equidistance. As the terminal scans input sig-
nals synchronously with the bus clock and the
bus runtime has a very small jitter, the input sig-
nals can be scanned equidistantly. Thus, the
measured results are particularly suitable for
use in closed-loop control.
The following configurations and measures are
recommended:
–
–
–
In applications in which an 8- bit resolution is
sufficient, group commands 7000
7100
multaneously. Scanning is synchronous with the
bus clock here too. Four channels require
<1500 µs.
Measured value acquisition: according to
standard method 1 or 2
In special cases, the group commands
(7x00
) can be an exception.
hex
Filtering: no mean-value generation
As total accuracy is often irrelevant in
closed-loop control tasks, filtering is not ne-
cessary. This increases the dynamic re-
sponse of the terminal and speeds up the
closed-loop control circuit.
Adjust the bus cycle time to the firmware
runtime
Example: in standard method 1, the firm-
ware runtime is <800 µs, i.e., the bus cycle
time should be set to 800 µs.
can be used to read four channels si-
hex
and
hex
37
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