2 - 10 WBPEEUI240766B0
Diagnostic, Security, and Integrity Checks
• ROM test.
• DPRAM test.
• NVRAM test.
• SRAM test.
• System reference checks.
• Configured channel reference checks.
• Unconfigured channel reference checks.
Diagnostics During Normal Operation
During startup, the ASI module verifies the checksum of the
PROM and nonvolatile RAM. Watchdog timers safeguard
against an A/D converter failure which would halt input scan-
ning. Input circuits are monitored for open circuits. Any errors
are reported to the controller through the I/O module status.
Certain failures detected by these diagnostics may result in
halting the I/O module.
Diagnostics on Reset
These tests include:
• PROM checksum verification.
• NVRAM checksum verification.
• DPRAM/SRAM verification.
• Processor instruction set tests.
• Timer test.
I/O Expander Bus Communication Security
Expander bus message integrity is maintained by checksum
calculations on each transmitted and received message or data
set.
Open Input Detection
The ASI module recognizes and reports any open inputs on
active channels by indicating bad quality on these channels.
The exception is for -10 to +10 VDC, 0 to 10 VDC, and 0 to
5VDC inputs.
Alarm and Exception Reporting
No alarm or exception reports are generated by the function
codes associated with the ASI module. The values input from
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