Chapter 4. CPU Operation
168 PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual GFK-2222AD
4.10.1 I/O Configuration
Module Identification
In addition to the catalog number, the programming software stores a Module ID for each configured
module in the hardware configuration that it delivers to the CPU. The CPU uses the Module ID to
determine how to communicate with a given module.
When the hardware configuration is downloaded to the CPU (and during subsequent power-ups), the
CPU compares the Module IDs stored by the programmer with the IDs of the modules physically present
in the system. If the Module IDs do not match, a System Configuration Mismatch fault will be generated.
Because I/O modules of similar type may share the same Module ID, it is possible to download a
configuration containing a module catalog number that does not match the module that is physically
present in the slot without generating a System Configuration Mismatch.
Certain discrete modules with both reference memory inputs and reference memory outputs will
experience invalid I/O transfer if incorrect configuration is stored from a similar mixed I/O module. No
fault or error condition will be detected during configuration store and the module will be operational,
although not in the manner described by configuration.
For example, a configuration swap between the IC693MDL754 output module and IC693MDL660 input
module will not be detected as a configuration mismatch, but I/O data transfer between the module and
the CPU reference memory will be invalid. If the input module (MDL660) is sent the configuration of the
output module (MDL754) with the following parameters:
Reference Address: %Q601
Module Status Reference: %I33
Hold Last State Enable
It will receive inputs at the module status reference %I33 and the status of the module will be received
at %Q601.
If the output module is sent the configuration of the input module with the following parameters:
Reference Address: %I601
Input Filter: Enable
Digital Filter Settings Reference: %I65
It will output values at the digital filter settings reference %I65 and the status of the module will be
received at %I601.
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