Output Image-Configuration & User-Defined Scale Limits; Input Image-Data And Status Words; Section 3.2 The Difference Between Channel Update Time And Step Response Time - Spectrum Controls SLC 500 User Manual

3-2 Chapter 3: Configuring the 1746sc-INI4I
NOTE
Section 3.2
The Difference Between
Channel Update Time
and Step Response Time
User's Manual Pub. 0300128-04 Rev. A
O:4.2. Alternatively, if you want to obtain the status of channel 2, you would
check the status word at address I:4.6.
The output and input image are described below.
Output Image—Configuration & User-Defined Scale Limits
The 8-word, output image (defined as the output from the SLC processor to your
module) defines how each channel on your module works:
The configuration words replace configuration DIP switches on your
•
module. Each word configures a single channel.
The user-defined scale limits define how your module scales analog input
•
values to a binary input register value, if one of the user-defined scale data
formats is selected.
Input Image—Data And Status Words
The 8-word, input image (defined as the input from your module to the SLC
processor) holds the data received by your module and provides the status
(configuration and operational state) of each channel.
Important – A data word is valid only when the channel is enabled and
there are no channel errors. A status word is valid only when the channel
is enabled, and the module has processed all configuration changes.
The speed of an analog module can be defined in 2 distinctly different ways:
either by the channel update time or by the full-scale step response time.
The channel update time is the time required for your module to sample
•
and convert the input signal of an enabled channel and make the resulting
data available to the processor.
The full-scale step response time is the time required for a channel's data
•
word to reach 95% of the expected, final value, given a full-scale step change
in the input signal. This means that if an input signal changes faster than the
full-scale step response time, the signal value provided to the processor has
not reached 95%.
The following figure illustrates the difference between channel update time and
full- scale step response time.