5-2
—Max Records: an unsigned integer representing the total number of records the log is capable
of holding. In order to maintain a one-for-one relationship in parallel logs (Sequence of Events
State and Sequence of Events Snapshot logs, for example), the maximum number of records that a
log can store is defined by the log that holds the fewest records. Logs capable of holding more
records are restricted.
QWindow Index tells the Modbus Master which 128-byte section of the log the Window is using to
retrieve the log. The block of Window Index Registers for the different logs begin at 38145. When
the Modbus Master writes a new value to the Window Index, a new section of the log will fill the
Window. For example, when the Index is 0000H, the first 128 bytes of the log are available in the
Window; when the Index is 0001H, the second 128 bytes of the log are available in the Window, and
so on. The designation “first 128 bytes of the log” is a physical description based on the absolute
addresses of the memory allocated to the log. The first (oldest) record in the log may not be located
at the beginning of the log.
—When a value other than FFFFH is written to the Window Index, the Index is updated and the log
is paused, preventing the addition of new records while the log is accessed. A30-second timer is
initiated on these writes. Should the timer expire (a new index is not written within 30 seconds),
the log will continue logging.
—Should multiple ports access the same log simultaneously, the log will pause while any 30-
second timer is running. The log will continue logging only when all ports time-out or write
FFFFH to their Index Register.
—When read, the Window Index returns the number of the Index currently in use by the Window.
When written, the Window Index sets a new Index for the Window to retrieve the log.
QWindow Mode defines the two available modes the Window may use to retrieve a log; Download
Mode and Time Stamp Mode. The Window Mode block begins at Register 38209.
—Download Mode: In Download Mode, the Log Window accesses consecutive 128-byte blocks of
the log. For example, when the Window Index is 0000H, the first 128 bytes of the log are
available in the Window; when the Index is 0001H, the second 128 bytes of the log are available
in the Window. The designation “first 128 bytes of the log” is a physical description based on the
absolute addresses of the memory allocated to the log. The first (oldest) record in the log may not
be located at the beginning of the log.
—Time Stamp Mode:. In Time Stamp Mode, the Log Window access the time stamps of the
records in blocks of 16 time stamps at a time. When the Window Index is 0000H, the time stamps
of the first 16 records (records 0–15) in the log are available in the Window; when the Window
Index is 0001H, the time stamps of the second 16 records (records 16–31) in the log are available
in the Window, and so on. The designation “first 128 bytes of the log” is a physical description
based on the absolute addresses of the memory allocated to the log. The first (oldest) record in the
log may not be located at the beginning of the log.
QLog Window: The Log Window is a 64-register, 128-byte view of a log. The Window Index defines
which part of a log is currently available in the Window. Log Windows begin at Register 38273.
QLog Reset: This Register (located at 57345), when written to, causes all logs to be cleared. This