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Data Transmission
Data Reception
Timing
Reports
Malfunction (MR)
70/722 Synchronous
Transmitter -Receiver
Buffer
•
The STRB executes a TC as indicated. When DSR and DeD from
the data set are present, the STRB responds to a CCM SEL with RDY. A
bit is received from the CCM on the Data lead and transferred to bit
storage. At the proper time, the STRB's transmit clock causes the stored
bit to be transferred to the data set TD lead with the same sense (lor 0)
as received from the CCM. Thereafter, so long as DSR and CTS are
!lresent, the STRB becomes RDY and transfers the second and subsequent
bits to storage and then to the TD lead until TERC is received along with
the last bit to be transmitted. After receiving TERC, the STRB inhibits
RDY, transfers the last bit to the TD lead, and terminates as
indicat~d.
While a TC is present, the STRB places a marking (1) bit on the TD
lead unless a spacing (0) bit is made available by the CCM.
•
The STRB executes an RC as indicated. When DSR and DCD from the
data set are present, the STRB is conditioned to transfer the first bit from
the RD lead to bit storage, using the character frame previously established.
The STRB then responds to a CCM SEL with RDY. The stored bit is trans-
ferred to the CCM on the Data lead with the same sense (lor 0) as received
from the RD lead. Subsequently, so long as DSR and DCD are present, bits
are transferred from the RD lead to bit storage and then to the CCM.
If
at
any time the buffer receives an ECC from the CCM, it adjusts the character
frame so that the next bit is the first of a sequence of eight bits in the
frame. After a TERC is received, the STRB inhibits RDY and terminates
as indicated ..
Upon entering the receive mode with DSR and DCD present, the STRB
does not transfer a bit to storage until the first bit of the character frame
comes up.
•
The STRB provides the bit or signal element timing for operation with
all data sets. This timing is derived from the modulation rate oscillators
in the CCM.
•
The Report signals to the CCM are encoded by the STRB to show the
following conditions:
Malfunction (MR)
Error (ER)
Ring (RR)
END
END and Error (EER)
• When a command is present, but after a RDY and prior to END; the
STRB indicates improper communication equipment and line conditions to
the CCM via a Malfunction Report (MR). AnMR is caused by the following:
1.
Transmit - Loss of the CTS signal from the data set, prior to TERC.
- Loss of the DSR signal from the data set.
2. Receive
- Loss of the DSR signal from the data set.
After an MR, the STRB drops the command which was present as it does
for a termination (TERC) as previously indicated and is conditioned to
accept a new command.
4-32
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