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Receive
Reports
Malfunction (MR)
Error (ER)
Ring (RR)
70/721 Synchronous
Data Set Buffer
• The buffer executes an RC as indicated, and is conditioned to start bit
detection when DCD is present. By means of bit timing which the buffer
receives on the data set SCR lead; a bit is transferred from the data set RD
lead to storage. The buffer then responds to a CCM SEL with RDY. The bit
is transferred to the CCM on the Data lead with the same sense (1 or 0) as
received from the data set. Subsequently, bits are transferred from the RD
lead to storage and then to the CCM until TERC is received. Thereafter, the
buffer inhibits RDY and terminates as indicated.
•
The Report signals to the CCM are encoded by the buffer to show the
following conditions:
Malfunction (MR)
Error (ER)
Ring (RR)
END
END and Error (EER)
•
When a command is present in the buffer, but after an RDY (except during
automatic calling) and prior to END; the buffer indicates improper commu-
nication equipment and line conditions to the CCM via a Malfunction Report
(MR). An MR is caused by the following:
1.
Transmit -
Loss of the DSR signal from the data set.
2.
Receive -
Loss of the DSR from the data set.
3.
Auto -Call -
A signal from the special feature.
After an MR, upon receipt of RAK from the CCM, the buffer terminates
the command and does not report ENDto the CCM. The buffer is then in the
quiescent condition.
•
When a command is present in the buffer, but after an RDY (except
where noted or during automatic calling) and prior to END; the buffer
indicates an error condition to the CCM via an Error Report (ER).
An
ER
is caused by the following:
1.
Transmit -
Loss of the data set CTS Signal, prior to receipt of
TERC.
2.
Receive -
Loss of the data set DCD signal, prior to receipt of
TERC.
3.
Auto -Call -
A signal from the special feature.
The buffer reports such conditions once per occurrence.
If
error and malfunction conditions occur simultaneously, only the MR
is indicated to the CCM.
•
The buffer is always conditioned to detect an RI signal from the data
set and report a Ring (RR)
to
the CCM. The buffer reports a Ring only once
pbr RI signal from the data set.
4-26
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