2220 Analog Input/Output Module
The 2220 analog subsystem provides 8 differential analog inputs, 8 analog
outputs and 8 digital outputs in a single module. The bipolar (±10 Volt) analog
inputs offer 15 bit resolution, and may be individually programmed to digitally
filter the incoming signal, providing increased stability. From 2 to 256 analog
samples may be continuously averaged at an update rate of 2.083 milliseconds.
The eight bipolar analog outputs have a resolution of 13 bits, and an output
range of ±10 Volt. Eight open-collector outputs are also available for driving
DC loads. Each output will handle up a .5 amp load and provides over-current and
short circuit protection.
Local CPU for Increased Performance
The model 2220 is equipped with a 16-bit processor to perform all on-board
related functions. This results in fast asynchronous update times without any
performance degradation the controller’s main CPU. Each I/O point is refreshed
every 2.083 milliseconds and made available to the main CPU via dual-port RAM
technology. Your Quickstep application program is free to interrogate analog
inputs and write to the outputs at any time without injecting lengthy conversion
delays into the execution time.
Isolation
All model 2220 inputs and outputs are optically isolated from the
controller’s CPU logic to reduce error-inducing ground-loops and increase
noise immunity. As with other analog modules offered by CTC, the analog ground
of each 2220 is transformer isolated locally, further reducing the potential for
ground interaction in a complex system.
Input Threshold Triggering
Each analog input may be locally configured to control an associated digital
output, based on reaching a predefined set-point. These set-points may be
dynamically adjusted from the controller’s program or via an operator
interface. Two set-points per channel are used to configure a hysterisis
boundary that prevents undesired crossover switching of the digital output.
Since the threshold sensing is handled locally on the 2220, it is not subject to
controller response times and is repeatable to within 2.25 milliseconds per
channel.
