User guide

Processor Modules (T7110, 11, 12, 20, 21, and 22)
4 (Issue 1) Industrial Control Services
In addition to running application programs, the main processor
takes care of system overhead, such as:
• Background diagnostics including voter tests, read tests of the
EPROMs, and read-write tests of the RAM (this automatic test
is also what re-educates a new processor).
• Communications processing including reading from and
writing to the communications modules every one millisecond
and checking the communications messages at the end of each
scan.
• Fault filtering and reporting (which are available through
W
INTERPRET’s fault status and fault history features).
• Reading the communications module’s real-time clock (if a
real-time clock communications module is installed).
I/O Processor
During each scan cycle the I/O processor receives voted input data
into its local RAM and transfers it to the shared RAM — making it
available to the main processor. After being processed by the main
processor, output data are placed into the shared RAM and read by
the I/O processor into its local RAM and written to the outputs.
The I/O processor also shares in managing system overhead. This
overhead includes:
• Background I/O processor tests (voter tests, read EPROM tests,
and read-write local RAM tests).
• I/O module tests (I/O module voter tests, logic loopback tests,
and coordinating other I/O module tests).
• Fault filtering and reporting (which are available through
W
INTERPRET’s fault status and fault history features).
Testing and Diagnostics
Each processor module’s error detection logic is periodically tested
to ensure its continued correct operation. Testing is done using
self-tests that are automatically scheduled by each processor
module’s real-time operating system.
Front Panel Indicators and Controls
Figure 3 shows the physical features of the processor modules. The
front panel of each module contains status indicators as well as a
reset button and a memory lock keyswitch.