DESCRIPTION AND OPERATION
2 - 8
I-E96-217A
®
do not match, the microprocessor stops resetting the MFT
causing a
time out
to occur.
If all tests pass, the SPM initializes all RAM memory locations
and begins to execute computer commands. It also sets the
front panel LED to solid green to indicate that the module is
on-line and operating correctly.
Other problems within the SPM can cause a
time out
to occur.
The microprocessor periodically resets the MFT preventing it
from ever timing out. If a condition exists for the SPM that
causes the microprocessor to fail or operate incorrectly, the
MFT will not be reset resulting in a
time out
.
STATUS LED INDICATOR
A single front panel module status LED indicator shows the
operating state of the SPM (i.e., normal operation or
time out
).
The MFT circuits on the SPM determine the module status and
light the LED accordingly. It lights green to indicate normal
operation; red for a
time out
.
A group of four status LEDs also indicate module operating
status. The microprocessor sets the LEDs to indicate the cur-
rent on-line test being run and its result, and the sequence of
computer commands and SPM replies.
explains the LED indications and
explains
corrective actions to take.
SERIAL PORT CONFIGURATION
Access to both SPM serial ports, port 1 and port 2, is available
at the P3 edge connector or at sockets XU37 and XU38. The
faceplate connector provides connection to port 2 only through
a ribbon cable connected to XU37. Refer to Table
and
for pin outs of P3, XU37 and XU38.
Figure
shows the pin numbering for the front panel,
NTCU01 and RS-232C cables. An explanation of the signals at
each wired pin follows. Refer to
for an explanation of
proper cable wiring and connections between the SPM and
Data Terminal Equipment (DTE) or Data Communication
Equipment (DCE).
The front panel and NTCU01 connectors are arranged accord-
ing to Electronics Industries Association (EIA) RS-232C stan-
dards. This standard identifies various interchange signals,
signal levels and pin connections that are available for serial
data transmission. The SPM can monitor or output the signals
required for data exchange between it and a DTE or DCE
device. An example of a DCE device is a modem; an example of
