Introduction
The 2760-RB Flexible Interface Module is a very old i/o processor which supports 3 serial ports.
Red LED
Normally, the Active/Fault status LED on a port is green, indicating that the port is active and well. One of the port's status LED went red permanently, indicating a fault condition. The configuration report agreed that the port has a fault, but that was about all. This was not good; it did not reveal if there was a configuration fault, or a hardware failure. And, if it were a hardware failure, it could be anything between the main processor's i/o bus, the slave processor, the shared memory, the actual RS232 driver, and the physical pins.
Memory Test
The shared memory test reported a fairly large number of stuck bits:
00 testing u409 program memory... FF testing u409 program memory... A5 testing u409 program memory... 5A testing u409 program memory... 00 testing u509 program memory... 5000:8407: wrote 00, read 08 5000:8427: wrote 00, read 08 5000:8447: wrote 00, read 08 5000:8467: wrote 00, read 08 5000:8487: wrote 00, read 08 5000:84A7: wrote 00, read 08 5000:84C7: wrote 00, read 08 5000:84E7: wrote 00, read 08 5000:8507: wrote 00, read 08 5000:8527: wrote 00, read 08 5000:8547: wrote 00, read 08 5000:8567: wrote 00, read 08 5000:8587: wrote 00, read 08 5000:85A7: wrote 00, read 08 5000:85C7: wrote 00, read 08 5000:9407: wrote 00, read 08 5000:9427: wrote 00, read 08 5000:9447: wrote 00, read 08 5000:9467: wrote 00, read 08 5000:9487: wrote 00, read 08 5000:94A7: wrote 00, read 08 5000:94C7: wrote 00, read 08 5000:94E7: wrote 00, read 08 5000:A407: wrote 00, read 08 5000:A427: wrote 00, read 08 5000:A447: wrote 00, read 08 5000:A467: wrote 00, read 08 5000:A487: wrote 00, read 08 5000:A4A7: wrote 00, read 08 5000:A4C7: wrote 00, read 08 5000:A4E7: wrote 00, read 08 5000:B407: wrote 00, read 08 5000:B427: wrote 00, read 08 5000:B447: wrote 00, read 08 5000:B467: wrote 00, read 08 5000:B487: wrote 00, read 08 5000:B4A7: wrote 00, read 08 5000:B4C7: wrote 00, read 08 5000:B4E7: wrote 00, read 08 5000:C407: wrote 00, read 08 5000:C427: wrote 00, read 08 5000:C447: wrote 00, read 08 5000:C467: wrote 00, read 08 5000:C487: wrote 00, read 08 5000:C4A7: wrote 00, read 08 5000:C4C7: wrote 00, read 08 5000:C4E7: wrote 00, read 08 5000:C507: wrote 00, read 08 5000:C527: wrote 00, read 08 5000:C547: wrote 00, read 08 5000:C567: wrote 00, read 08 5000:C587: wrote 00, read 08 5000:C5A7: wrote 00, read 08 5000:C5C7: wrote 00, read 08 5000:D407: wrote 00, read 08 5000:D427: wrote 00, read 08 5000:D447: wrote 00, read 08 5000:D467: wrote 00, read 08 5000:D487: wrote 00, read 08 5000:D4A7: wrote 00, read 08 5000:D4C7: wrote 00, read 08 5000:D4E7: wrote 00, read 08 5000:E407: wrote 00, read 08 5000:E427: wrote 00, read 08 5000:E447: wrote 00, read 08 5000:E467: wrote 00, read 08 5000:E487: wrote 00, read 08 5000:E4A7: wrote 00, read 08 5000:E4C7: wrote 00, read 08 5000:E4E7: wrote 00, read 08 5000:F407: wrote 00, read 08 5000:F427: wrote 00, read 08 5000:F447: wrote 00, read 08 5000:F467: wrote 00, read 08 5000:F487: wrote 00, read 08 5000:F4A7: wrote 00, read 08 5000:F4C7: wrote 00, read 08 5000:F4E7: wrote 00, read 08 FF testing u509 program memory... A5 testing u509 program memory... 5000:8407: wrote A5, read AD 5000:8427: wrote A5, read AD 5000:8447: wrote A5, read AD 5000:8467: wrote A5, read AD 5000:8487: wrote A5, read AD 5000:84A7: wrote A5, read AD 5000:84C7: wrote A5, read AD 5000:84E7: wrote A5, read AD 5000:8507: wrote A5, read AD 5000:8527: wrote A5, read AD 5000:8547: wrote A5, read AD 5000:8567: wrote A5, read AD 5000:8587: wrote A5, read AD 5000:85A7: wrote A5, read AD 5000:85C7: wrote A5, read AD 5000:9407: wrote A5, read AD 5000:9427: wrote A5, read AD 5000:9447: wrote A5, read AD 5000:9467: wrote A5, read AD 5000:9487: wrote A5, read AD 5000:94A7: wrote A5, read AD 5000:94C7: wrote A5, read AD 5000:94E7: wrote A5, read AD 5000:A407: wrote A5, read AD 5000:A427: wrote A5, read AD 5000:A447: wrote A5, read AD 5000:A467: wrote A5, read AD 5000:A487: wrote A5, read AD 5000:A4A7: wrote A5, read AD 5000:A4C7: wrote A5, read AD 5000:A4E7: wrote A5, read AD 5000:B407: wrote A5, read AD 5000:B427: wrote A5, read AD 5000:B447: wrote A5, read AD 5000:B467: wrote A5, read AD 5000:B487: wrote A5, read AD 5000:B4A7: wrote A5, read AD 5000:B4C7: wrote A5, read AD 5000:B4E7: wrote A5, read AD 5000:C407: wrote A5, read AD 5000:C427: wrote A5, read AD 5000:C447: wrote A5, read AD 5000:C467: wrote A5, read AD 5000:C487: wrote A5, read AD 5000:C4A7: wrote A5, read AD 5000:C4C7: wrote A5, read AD 5000:C4E7: wrote A5, read AD 5000:C507: wrote A5, read AD 5000:C527: wrote A5, read AD 5000:C547: wrote A5, read AD 5000:C567: wrote A5, read AD 5000:C587: wrote A5, read AD 5000:C5A7: wrote A5, read AD 5000:C5C7: wrote A5, read AD 5000:D407: wrote A5, read AD 5000:D427: wrote A5, read AD 5000:D447: wrote A5, read AD 5000:D467: wrote A5, read AD 5000:D487: wrote A5, read AD 5000:D4A7: wrote A5, read AD 5000:D4C7: wrote A5, read AD 5000:D4E7: wrote A5, read AD 5000:E407: wrote A5, read AD 5000:E427: wrote A5, read AD 5000:E447: wrote A5, read AD 5000:E467: wrote A5, read AD 5000:E487: wrote A5, read AD 5000:E4A7: wrote A5, read AD 5000:E4C7: wrote A5, read AD 5000:E4E7: wrote A5, read AD 5000:F407: wrote A5, read AD 5000:F427: wrote A5, read AD 5000:F447: wrote A5, read AD 5000:F467: wrote A5, read AD 5000:F487: wrote A5, read AD 5000:F4A7: wrote A5, read AD 5000:F4C7: wrote A5, read AD 5000:F4E7: wrote A5, read AD 5A testing u509 program memory... 00 testing u609 program memory... FF testing u609 program memory... A5 testing u609 program memory... 5A testing u609 program memory...
The Fix
Having identified the faulty integrated circuit, it was replaced with a modern equivalent of higher access speed. This enabled a legacy system to continue running, and saved another part from entering the garbage disposal.
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