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5. Turn on the 3274.
6. Run the wrap test by performing an AL T2 IML. Suc-
cessful completion of the wrap test is indicated by the
operational indicator (8 4 2 1) display of 1000.
Warning: Remove the jumpers that were placed on the
OIA-AI board before reconnecting the communication
cable to the modem. For V.35, restore card G2jumper
from
E
to F. See Figure C-17.
5.3.3 Loop Wrap Test
The loop wrap test can be initiated by a normal 1M
L
or an
ALT2 IML as follows:
Normal IML - With the diskette customized for loop, a loop
wrap test will be initiated each time a normal IML is per-
formed. If the wrap test fails, a blinking 8 4 2 1 code of
0111 will be indicated. The attached display on port 0, or
at the 3274, will display one of the following:
0111 013 -
Indicates a failure from the HPCA to the loop
adapter.
0111 014 -
Indicates that the Loop Station Connector
(LSC) wrap test has failed.
Use the chart below to convert display codes to 8 4 2 1
indicator codes.
Codes at Display AO
0111--013
0111-014
0111 - 021 or 002
0111 -
a
16 or 00 1
0110 - 005
0110 --- 009
Codes in
8 4
2
1
Indicators
0111- 1101
0111 --1110
0111 -- 0010
0111 - 0001
0110 - 0101
0110 - 100 1
ALT2 IML - The loop wrap test is initiated by holding the
ALT2 switch in the 2 position and momentarily pressing
the IML pushbutton.
The following action should be taken if the wrap test fails:
1.
If
the 8 4 2 1 code is "013", change cards 13 and 14.
2.
If
the 8 4 2 1 code is "014":
a. Change card 14.
b. Check the internal I/O cable in board socket Y1 and
the external I/O communication cable for defects.
See Figure 5-6.
5,3.4 Loop Indicators
• Machine Check Indicator - Indicates that a problem is
internal to the 3274. When this indicator is on, run the
Loop Wrap Test (see paragraph 5.3 .3).
~
• OK (Line Ready) - Indicates that a valid message was
received within the last 8 seconds. If this indicator does
not come on, use the Host/8100 maintenance procedures
to isola te the problem.
• External Check Indicator - Indicates that errors are
external to the 3274. If this indicator is on, use the
Host/8100 maintenance procedures to isolate the
prohlem.
The loop indicators described above are shown in Figure D-2.
5-14
5.4 2400-,4800-, and 9600-bps Integrated Modems
The 2400-,4800-, and 9600-bps Integrated Modems connect
the 3274 Model SIC to nonswitched telephone lines. These
modems operate in either ESC or SDLC; the 3274 Model
SIC must be equipped with CCA or HPCA. Figure 5-10
shows the communication line flow.
5.4.1 2400-bps Illtegrated Model11 (Featllre
Code 5640)
• Microprocessor based
• Half speed of 1200 bps
• Operates in duplex Illode over a nonswitched four-wire
communication channel in either point-to-point or
multipoint attachment.
• Central site must provide an IBM 3863 Modell modem.
5.4.2 4800-bps Illtegrated Modell' (Featllre
Code 5740)
• Microprocessor based
• Half speed of 2400 bps
• Operates in duplex mode over a nonswitched four-wire
communication channel ill either point-to-point or
multipoint attachment.
• Central site must provide an IBM 3864 Modell modem.
5.4.3 9600-bps Illtegrated Modem (Featllre
Codes 5840 and 5842)
• Microprocessor based
• Half speed of 4800 bps
• Point-to-point (Feature Code 5840)
This attachment operates in duplex mode over a non-
switched four-wire communication channel. The
central site must provide an IBM 3865 Modell modem.
• Multipoint
(Fe~ture
Code 5842)
This attachment operates in duplex Illode over a non-
switched four-wire cOlllll1unication channel. The
central site must provide an IBM 3865 Model 2 modem.
5.4.4 Line Attachments
5.4.4.1 Multipoint Network Operating Speed
In a Illultipoint nonswitched network, the operator, at the
master modem or through host programming, can cause the
3274 Integrated Modem
to
adjust its operating speed to
half speed. A reduction to half speed cannot, however, be
done by the 3274.
5.4.4.2 Point-to-Point Network Operating Speed
In a point-to-point nonswitched network, the operating
speed is controlled by the speed switch at the master modem.
'-
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