IBM 3745 Service Functions page 259

SIT
Scanner Interface Trace (SIT)
The scanner interface trace (SIT) function is used to collect the events that
occurred on a given line and the checkpoint entries.
These events are recorded in a TSS internal buffer and can be sent to the
MOSS via the CCU storage area dedicated to MOSS/TSS communications.
The SIT is similar to the SIT available in the host. The 3745 SIT is called
internal SIT (I-SIT), and the host SIT is called external SIT (E-SIT).
The main differences are:
• For the E-SIT, the contents of the buffer are continuously sent to the host.
• For the I-SIT, the buffer normally works in wraparound moBe and is trans-
ferred to the MOSS only on request. If you are not in wraparound mode,
and when the buffer is full, the trace is frozen (the trace is stopped but the
buffer is not released).
• In the host you can print the trace on 132 characters, this means
hexadecimal and translated data are visible at the same time.
In the MOSS corisole you can only display hexadecimal or translated data
at one time (see "Display I-SIT Buffer or File" on page 12-9).
The restrictions are:
• The buffer size is 8KB maximum.
• A maximum of four traces per scanner can be started according to the line
speed:
High-speed line (from 230 kbps for TSS and 1.5 Mbps for H PTSS -
maximum speed for HPTSS is 2.048 Mbps): only one trace in a buffer of
8 kbytes.
A 56 kbps line trace takes all the possible buffer space. Therefore, no
other SIT can be started after a 56 kbps line SIT.
Low-speed line (below 56 kbps): four traces in four buffers of 2KB each.
• If an E-SIT is running for a given line, an I-SIT can not be started on this line
(or vice-versa).
How to use the host SIT and SIT field details is described in the ACFITAP
manual, SC30-3143.
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3745 Service Functions
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