Specifications
Analog Input Modules
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STB ACI 1230 Functional Description
Functional
Characteristics
The STB ACI 1230 module is a two channel module that handles analog input data
from two field sensors operating in a 0 to 20 mA current range. The following
operating parameters are user configurable:
z offset and maximum count on each analog input channel
z a sampling of analog input values used to average the signal
Using the RTP feature in your NIM, you can access the value of the following
parameters:
z Offset
z Maximum Count
z Averaging
Refer to the Advanced Configuration chapter in your NIM manual for general
information on RTP.
Offset and
Maximum Count
You may apply an offset value to the low end of the operating current range and a
maximum count to the high end of the current range. This feature allows you to
calibrate the analog input channels to match your equipment.
Offset is configured as a signed integer. It may be a decimal or hexadecimal value
in the range -8191 to +8191 (0xE001 to 0x1FFF), representing a current offset in the
range -5.12 to +5.12 mA. By default, the offset on both channels is 0 (indicating no
offset applied).
Maximum count is configured as a decimal or hexadecimal value in the range
23 800 to 32 760, representing a current in the range 14.88 to 20.48 mA. By default,
the maximum count on both channels is 32 000 (indicating no gain applied).
Offset and maximum count may be applied on each channel independently.
These parameters are provided only for sensor compensation, not for scaling. The
module is able to measure over the physical range of 0 to 20 mA. An offset
adjustment will move the interpretation of 0, and a max count adjustment will move
the interpretation of only the high end of the range.
An ideal linear current representation (one without offset or max count adjustments)
is interpreted using the
formula:
Note: Standard NIMs with firmware version 2.0 or higher support RTP. RTP is not
available in Basic NIMs.
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