NTP-002 AT&T 356-024-510
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breaks the daisy chain at that bay, resulting in none of the subsequent bays (bays farther away from the
daisy-chain terminal than this off-line bay) being able to communicate via the daisy-chain data bus. If this
condition occurs, the daisy-chain break can be temporarily bypassed by unplugging the two data-bus cables
from the two daisy-chain connectors on the distribution panel at the top of the bay and plugging these two
cables together. This restores daisy-chain continuity to the subsequent bays.
With daisy-chain communication, all on-line bays are listening to commands as they are being entered.
Either one or all bays can be addressed in asingle command. Once an addressed bay begins its response, it
will complete its output before another bay begins its response. The addressed bays will not necessarily
respond in the same order as their daisy-chain lineup positions.
In adaisy-chain environment, one bay is the echoing bay. This bay echoes each character entered at the
daisy-chain terminal and reports any syntax errors via the daisy-chain data bus. The echoing bay is the last
on-line bay, i.e., farthest from the daisy-chain terminal, in the daisy chain. If the echoing bay goes off-line,
the next preceding on-line bay becomes the echoing bay- When echo is passed to the next preceding on-line
bay, an ECHO TRANSFERREDTO THIS BAY message is transmitted over the daisy-chain data bus by the new
echoing bay.
If anonechoing on-line bay goes insane, the next preceding on-line bay becomes an echoing bay. This results
in aduplicate echo over the daisy-chain bus, since the original echoing bay continues to echo.
D. General Operating Information
Baud rate of the daisy chain is determined by the communication device (modem, TTY, etc.) attached to tha-
daisy-chain bus. The baud rate switches must be set on the Control and Access Unit in each and every bay
to be consistent with the daisy-chain baud rate. The baud rate of any device plugged into the Control and
Access Unit faceplate connector must be consistent with the faceplate baud rate switch settings on the
Control and Access Unit.
E. Handheld Terminal
The Type 12 pocket terminal has multifunction keys on its keypad. To activate the second function of akey
(printed in white on ared background), press the SHIFT key at the top left-hand corner of the keypad before
pressing the desired function key. If you make amistake, you can backspace by pressing CONTROL Hor
SHIFT3, or you can delete the whole line by pressing SHIFT @. Processes can be stopped using CTRLX(CONTROL
X), which invokes the same function as CANCELor DELETEon most full-sized terminal keyboards.
If for some reason the user cannot regain control of the system, CTR1O(Control “Zero”) will abort’ all
processing. This invokes the same function as BREAKor ESCAPEon most full-sized terminal keyboards.
Caution: The use of CTRlO,BREAK,or ESCAPEis intended as ararely-used immediate
halt. Use of this function may cause database inconsistencies between the CA U
and CH-PR. For this reasonj C4NC& DELET4or CONIROlXare the preferred halt
functions. Recovery from this type of abort should include an examination of the
CA Uand CH-PR data bases for consistency. Test setup status should also be
examined.
F. Helpful Hints far SuccessfulCommand Usage
Only one command may be entered at atime. All requested processing for acommand must be completed
before the next command is entered. Entering anew command before processing has been completed by all
bays addressed by the previous command, can produce unpredictable results.
Sometimes auser might enter acommand and not receive aresponse or an error message. This will most
likely happen if the user enters avalid command with avalid address format, but the address used does not
belong to any of the bays on the daisy chain. Each bay reads the command line, recognizes the command
