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TROUBLESHOOTING
ECHO TEST
5 - 2
I-E96-620A
®
the reply display. These error codes are displayed in place of
the byte when the respective error condition occurs:
*P
- parity error
*F
- framing error
*O
- overrun error
*D
- data carrier detect error
*L
- bytes lost by the diagnostic port but not lost by the
interface normal operation
The interface does not allow the diagnostic port to degrade the
performance of the normal interface and host computer opera-
tion. Because of this, the diagnostic port can lose information
which the interface is correctly processing, particularly if the
diagnostic port is set to a slow communication rate. The
*L
error code indicates this condition. When this happens, the
interface stops displaying the rest of the command reply. It dis-
cards intervening commands and replies which it does not
have time to display. It then continues the display with the
beginning of the next command. Enter
- to suspend the
diagnostic port dump for examination. The display stops
updating while it is suspended.
Press
- again to unsuspend. While the display is sus-
pended, the diagnostic port continues to store information. So,
if it loses characters because of the suspension the
*L
code will
appear some time after the unsuspension.
The diagnostic port is always active and may be used by
cabling a terminal to it, matching the selected baud rate, data
transmission characteristics, and selecting normal operation
(SIM option).
ECHO TEST
This test provides a simple means of testing the computer to
interface connections. Enable this test by setting the SIM
option switch (SW2), position 3, to 1. When the SIM executes in
this mode, the SIM LEDs go through their normal exercise rou-
tine, ROM test and RAM test as in normal operation. Then they
display a count of characters input to the SIM in the echo
mode.
To use this feature, cable a terminal to the port being tested
using a standard RS-232-C cable. The port data characteris-
tics and communication rate of the terminal must be set to
match those settings on the SIM.
The SIM echoes characters entered on the terminal keyboard.
Those characters appear on the terminal screen. If the SIM
finds any framing or parity errors, it will not echo that charac-
Ctrl
S
Ctrl
S