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12-1
ANALOG INPUT MODULE
General Description
The Analog Input (AI) modules have 8 or 16 inputs. The modules sample and convert analog
data into digital format and transfer the digital data to the CPU module.
The following modules are available:
•
8
AI ±20 mA (supports 4-20 mA)
•
16 AI ±20 mA (supports 4-20 mA)
•
8 AI ±5 V (supports 0-5 V and 1-5 V)
•
16 AI ±5 V (supports 0-5 V and 1-5 V)
The module’s analog-to-digital conversion resolution is 16 bit (including sign). Each input is
fully isolated from the other inputs on the module and also optically isolated from the module
internal circuits. The modules are fully calibrated and can be tested and recalibrated in the
field.
The measured values are digitally filtered to reduce the 50 or 60 Hz noise. The user can select
the filtering frequency per module.
The measured values can be smoothed by digital filtering. Smoothing is accomplished by
calculating the running average values of a defined number of converted analog values
(samples). The user can select the level of smoothing per module. The higher the smoothing
level chosen, the more stable is the smoothed analog value and the longer it takes until the
smoothed analog signal is applied after a step response.
The user can select how the analog values are represented to the user application program as
unit-less numeric values or as scaled values that represent certain Engineering Units (EGU).
Each AI module can include an optional plug-in floating 24V DC power supply to power
external devices.
Each analog input has two status LEDs:
•
UF - indicates Underflow when lit
•
OF - indicates Overflow when lit
For a description of I/O module construction, location, LEDs, TB holder, and other common
I/O module features, see the I/O Modules chapter above.
For details on specific AI parameters and configuration, see AI Module Configuration below.
Figure 12-1 provides a general view of the ACE3600 AI module.