RCA 70/700 Series Reference Manual page 32

OW CONSTRUCTION
EXAMPLE NUMBER
1 (83-B-X)
OW-l Explanation
v -
Polling Answer-
Back from Remote
Terminal (No Traffic)
eeM
Initialization
• Table 2-1 is an OW table established for the proper CCM detection and
control of a fictitious 5-level, semi-automatic, multi station, half-duplex,
private line, telegraph system identified as 83-B-X. The control codes
and control sequences which must be set into OW s ha ve been defined as
follows:
Function
Code
start of Message (SOM)
ZCZC
End of Message (EOM) NNNN
start Code Answer-Back V
End-of- Transmission Code S
(EOT)
The SOM and EOM perform their normal function, but because this
system allows multiple messages in each transmission, the EOM of the
last message is followed by an S. The V is received by the CCM from a
remote terminal if that terminal has been polled, but has no traffic to send
o
This particular example does not require the accessing of OW-2. The
bit settings 0 through 16 of OW-1 are set to 1 or 0 to reflect the necessity
of:
1 - take action
o -
do not take action
Based upon these OW requirements, the CCM hardware is set to reflect
in the LSWs the bit settings for the initial conditions: Receive/Transmit
status, NDB/ out of data block, and the sequence counter
0
• 1.
Receive/Transmit set to 1 - present only when receiving NDB to
o -
system should be out of data block when V is received
o
Sequence
counter setting is not necessary when this character could be
received
o
2. OW-1 Bit Settings:
2, 1, 0 (Action Control) - 001, unconditional action.
3 - 0 Not Used.
2-4
4 - 0 V should not set NDB.
5 - 0 V should not reset NDB.
6 - 0 Do not inhibit resetting of sequence
counter.
8, 7, - 00 will not effect sequence counter
when hit 6 is set to
O.