IBM 2790, Manual

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Note:
Blank columns read by a 1035 or 2791 Badge
Reader or blanks entered through a Digital Device
Read-In attachment may or may not be included in the
data transmitted to the systems controller depending on
the setting of the delete-blanks option. If delete-blanks
is OFF, blanks are transmitted to the system controller
as X‘40’. If delete-blanks is ON, the blanks are deleted
from the data sent to the system controller. In either
case, the length check does not include blank charac­
ters.
Digit Check
This check permits the user to instruct the 2715 to make
one digit check per data entry. The digit to be checked
may have the value 0 through 9 and must be located in one
of the high-order positions (1 through 15) of the data entry.
If the user omits this check (null), the 2715 does not make
a digit check. When specifying the digit check, the user
should also specify the error guidance lamp to be lit if the
digit to be checked from the data entry is not equal to the
digit value supplied.
If an error is detected when making the length or digit
check, the 2715 will discard the data received from the
erroneous data entry and return the user-specified error-
guidance code. The 2791 operator is notified via the error
guidance light and may examine the media in question and
restart the data entry. If the entry is accepted this time,
the 2715 will advance the 2791 to the next step.
The operator may request “next guidance” if he is un­
certain which step was in error. The 2715 will return the
original guidance light for the step that was in error.
Other 2790 Transmission Line Error Checks
In addition to the preceding, the 2715 performs the following
error checks on data received from the 2790 transmission
line:
AS address changed
Device address changed
Abnormal status for end request
Data request overrun
Null acknowledgment overrun
Data character comparison
Status character comparison
If the 2715 detects one of these error conditions, it will
discard the data in question and cause the following indica­
tions to the 2791,1035, or 2795/2796 operator.
2791 Area Station Indications
1. Repeat/Clear lamp will be lit.
2. Card or badge will be held.
The operator clears this condition by pressing the Clear
button. This extinguishes the error lamp and releases the
media (card or badge). Guidance reverts to that designated
for the step in error. The operator may retry the step by
inserting the proper media.
1035 Badge Reader Indications
1. Repeat lamp will be lit.
2. Badge is held.
The operator presses the Clear button, which extinguishes
the Repeat lamp and releases the badge. The operator may
then re-enter the badge.
2795/2796 Data Entry Unit Indications
1. Error indicator/reset button will snap into view.
2. Entry request lever remains in latched position; the
card or badge cannot be removed.
The operator resets by pressing the error indicator/reset
button, which releases the interlock on the entry request
lever.
E R R O R A T T H E TR A N SM ISSIO N C O N T R O L U N IT
2715 Error Recording
The following description applies to all 2715-detected errors
with the exception of status-register checks, which result in
a hard stop.
Error recording in the 2715 consists of a 28-byte error
buffer, resident control program to load errors into the error
buffer, a nonresident program to move error information from
from error buffer to disk storage, and a nonresident program
to format the error transaction before placing it on-line
to the processor.
Each single error is placed in the error buffer as a four-
byte error record. This error record consists of a one- or
two-byte address followed by status information detailing
the error.
When the error buffer becomes filled or once an hour,
whichever occurs first, day and time-stamp data is attached
and the error data is transferred to the error log maintained
on the disk. The error log consists of eight fixed sectors;
each sector can accumulate a total of 42 errors.
When an error-log sector becomes filled, an error message
containing the data is automatically formatted and trans­
ferred to System/360 for data-set logging and later retrieval.
The contents of a partial error-log sector can be transferred
on a demand basis at any time.
The data contained in a 2715 error message consist of a
single transaction of 215 bytes, and represents one sector’s
worth of error recording.
2715 to System/360 error messages are not received by
the user but are routed by BTAM for data-set logging.
I Upon CE initiation of the Environment Record Edit and
Print (EREP), the proper formatting of these error records
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