10.2 Self-Test Diagnostics At Power-Up; Power-Up Diagnostics - Honeywell Series 8 I/O User Manual

10. Series 8 I/O Troubleshooting
10.2. Self-test diagnostics at power-up

10.2 Self-test diagnostics at power-up

Power-up diagnostics

TIP
Unlike C300, the Series 8 I/O modules do not have an alpha-numeric display
for displaying test codes.
Series 8 I/O modules run the following self-tests (transparent to the user) every time the
module boots up following a power-on or reset or reboot.

After the hardware and memory initializations TC/RTD IOMs reload the FPGA
(field-programmable gate array) image from the flash memory to the FPGA.

All IOMs check the validity of the application image by computing the Cyclic
Redundancy Check (CRC) of the flash memory where application image is stored. If
the CRC comparison is valid, the module transfers to the application mode.
Otherwise, the module stays in the boot mode waiting for a firmware download
operation.

In the application mode hardware and memory is re-initialized for application
operation and module ID set by the address jumpers is checked.
Modules then execute a series of self diagnostics as listed below (any failure
detected results in hard fail of the IOM.)

CPU: Checks the CPU registers by writing and reading back specific patterns
and execution of a set of logical operations.

RAM contents: Test patterns are written and read back to all RAM locations.
This test ensures that each RAM bit can store and retrieve 0 and 1 without any
error.

Address lines: CPU address lines are tested by walking 1's and 0's. This test
ensures that each address lines can be changed independent of others.

Flash contents: CRC of the application image is checked again.

Stack: A test pattern is written to the top of the stack which is confirmed read
back. This pattern is used for the background stack diagnostics during normal
operation of the module.
During the normal operation the above self-diagnostics run as low-priority
background activity.

Application specific database objects are created and task scheduler is initialized.
Watchdog circuitry and IOL are enabled and normal operation of the module begins.
256 Series 8 I/O User's Guide
Honeywell
R500
April 2017