Table of Contents
Advertisement
MONITOR MODE
Monitor mode is an added multipoint feature available as
an option to the 13260C and 13260D interfaces. It allows a
terminal to monitor the data transfers between the com-
puter or driver terminal (refer to Driver Mode) and other
multipoint terminals on the same communication line.
This is a useful technique when developing communica-
tions programs or testing multipoint networks.
The monitor must be placed in the line between the com-
puter and the other terminals in order to monitor both
sides of the communication exchanges. Figure 5-18 shows
a sample communication line using a terminal in monitor
mode. (Note that the monitor cannot detect data sent from
terminal AA to the computer.)
Note that the monitor will not respond to poll or select
sequences addressed to it while in Monitor Mode.
Once the Monitor option has been installed (refer to Sec-
tion VII Installation for procedures), Monitor mode is
selected by the following:
Step 1.
IBI ,IBI (...
key down).
Step 2. •
,IE
Step 3. •
BII
(The DISPLAY FUNCTIONS indicator
should begin blinking.)
Data Communications
Pressing the DISPLAY FUNCTIONS key again will turn
off the indicator and return the terminal to normal
operation.
While in Monitor mode data communications between the
computer and ((downstream" terminals will be displayed
on the monitor. Data from terminals will be framed in left
and right arrows ( <data> ) and will include control and
block check characters (see figure 5-19). All untranslata-
ble EBCDIC characters will be displayed as ((?" characters.
In group poll operations the last three characters of the
poll sequence (second
II ,
ENQ, PAD) may be distorted due
to the response of polled terminals (see figure 5-20). Once
a terminal detects the first double quote character (
II),
it
begins its response with a transition on the Request to
Send Line (CA). This causes the monitor to begin watch-
ing for data from the terminal instead of the computer.
This distortion occurs only within the monitor and does
not affect the operation of either the computer or the other
terminals.
If the monitor terminal is configured with a communica-
tions buffer that is smaller than either the computer or
responding terminals, a data overflow may occur. A cancel
character (octal 030) will be displayed at the point where
the data overflow occurred (see figure 5-21). To prevent
data overflow, make sure that the buffer used in the
monitor is at least as large as the largest buffer used by
any responding terminal. (Refer to the Installation section
for buffer configuration information.)
HI! -,
1 -
c=
_
COUPLER/MODEM
Figure 5-18. Communication Line Using a Monitor
5-47
Advertisement
Table of Contents
