IBM 2790, Manual

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To Host
2715 No. 1 Servicing
Segments C and D.
2715 No. 2 Servicing
Segments A and B.
2715 No. 2 Equipped
with Line Transfer Switch.
# Figure 18. Line Transfer Switch
Selective Features for 2715 Model 1
The following selective features can be attached to the 2715
Model 1 only.
Local 2740-1 Adapter
The Local 2740-1 Adapter is a standard feature for the
| 2715 Model 2 and a recommended optional feature for the
2715 Model 1. This feature permits attaching an IBM 2740
Communication Terminal Model 1 within 40 wire feet of
the 2715. When attached, the 2740 operates as a console
device for communication with both the 2715 and the host
CPU. The 2740 is used in the following applications:
• Print operator awareness messages
• System/360 message printout
• Input transaction logging
I * User-defined message to the CPU
• Control requests to the 2715
The 2740 must be in communication mode and must
have power on and paper in the carriage when the 2715
tries to send it a message; if not, an audible alarm is sounded
| (if the 2740 alarm-restore parameter is specified), catalog
I
number X‘89’ is posted in the CE/operator panel lights,
and the undeliverable transaction is routed to the CPU
problem program with the proper error code.
2740 to System/360. The communication between the 2740
and the System/360 is defined and implemented by the user
in the System/360 problem program. The procedure for
entering a message to the System/360 from the 2740 is:
1. Press Line Bid (start of text)
I 2. Enter control digit (0-9)
I 3. Enter text (optional)
4. Press EOT (end of text)
The line bid initiates the connection with the 2715 and
allows the 2740 operator to enter the desired control char-
I
acter. The control character (described under “2715
Operational Characteristics”) is placed in the transac­
tion-control byte of the transaction being sent to the
System/360. The time when the request was made is stored
in the transaction header (using 24-hour clock). The text
| (if provided) is stored in the text portion of the transaction.
When EOT is pressed, the transaction is sent to the
System/360 if the channel or data link is available. Neither
the Bid nor the EOT are stored in the transaction. The text
portion may contain up to 247 characters. If 247 charac­
ters are exceeded, the 2715 disregards the transaction and
prints “ERR” .
Transactions successfully entered from the 2740 that
contain a transaction-control digit (0 through 9) are for­
warded to the System/360 in the same format as any other
2715-to-System/360 message. The area station and device
addresses are set to zero (X‘00’) indicating a 2740 message.
The user may specify any use he wishes for the transac­
tion-control digit (0 through 9); the 2715 treats all
digits (0 through 9) in the same manner.
I If more than about 30 seconds elapse between entering
two successive characters, the 2715 causes the 2740 to
■ print “ERR” , returns the 2740 to standby (ready for
I another bid), and discards the partial message entered.
System/360 to 2740 . System/360-to-2740 transactions
must follow the same format as other output messages to the
2715. Messages for the 2740 must have a message-control
character X‘04’ and a transaction-control character X‘F B \
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