IBM 3741 Data Station Reference Manual page 98

Status Message Format
A status message is sent to the remote station after the 3741
has responded negatively to a remote station's line bit request,
or responded negatively to a multipoint select, or after the
3741 has prematurely terminated a transmission or reception
of a message. In transmit mode (T, P, B,
J,
K, I, or D), this
occurs when a transparency check, disk error, line check,
received data block error, disk full error, disk accessibility,
incorrect data set label, or message aborted (after transmit-
ting a block four times) condition has been encountered. In
receive mode (R, BT, KT, IT, or DT) this occurs when a
wrong length check, disk(s) full, line check, disk accessibility,
write protect, or disk error condition is encountered. Also,
a status message is sent when RESET is used to abort the
transmission or reception of data. The 3741 will attempt to
send status on a point-to-point network. On a multipoint
network, the control station must poll for the status message.
The status message is sent with the following line control
format:
Displayed Error Indicator
Character
E
3741 N
Q
pro- A
cessing C 0
unit
K
t
S
v
S
o
%
T
H X
E
T
X
A
C
K
E
a
T
Note: On multipoint networks, an additional error indicator
character, a slash (/) can be sent with a status message. This
error indicator character is sent when the 3741 is selected
but is not ready. However, the slash (/) is not displayed on
the status I ine as are the other error indicator characters.
BSC CE Status Line
The BSC CE status line, primarily for use by customer engin-
eers, appears whenever a communications mode is selected.
The BSC CE status line is on line 6 of the display. The in-
formation displayed indicates the following conditions:
• Data terminal (3741) ready (DTR)
• Data set (modem) ready (DSR)
• Request to send (RTS)
92
• Clear to send (CTS)
• Number of incorrect CRC's in receive mode
• Number of NAK's sent in transmit mode
• Number of two-second timeouts
• Number of three-second timeouts
Figure 47 shows the format of the BSC CE status line.
For the DTR, DSR, RTS, and CTS positions, either a zero
(0), indicating the condition is not present, or a one (1),
indicating the condition is present, is displayed.
The four counters, CRC, NAK, 2-second timeout, and 3-
second timeout, are three position counters that are incre-
mented each time the condition occurs.
Error Recovery Procedures
There are several different types of errors that can occur:
1. Errors for which there is no error indication to the
operator and from which the 3741 can automatically
recover. An example is when a read error occurs and
the 3741 retries the read and the operation is success-
ful. (The 3741 retries read errors 11 ti mes before
displaying an error to the operator.)
2. Errors for which there is an error indication to the
operator (but no operator intervention is required)
and errors from which the 3741 can automatically
recover. (This type of automatic error recovery is
only available on switched networks.) An example
of this type of error is the remote abort error. When
this type of error occurs, the 3741 will answer a tele-
phone call and either transmit or receive data begin-
ning at the same place as the original call. However,
if the transmit/receive mode was selected, and the
error condition occurred during the receive mode,
the 3741 will answer a telephone call and receive the
data beginning at the receive mode start point.
3. Errors that occur when usi ng the 3713 unattended
print function while the first data set received is on
disk 2. The following section explains the operator
error recovery procedures.