IBM 7852-400 DIP Switch Settings
If you are using a 7852-400 modem to enable service processor communications, for proper operation, the
dual inline package (DIP) switches must be set according to the following table:
Switch Position Function
1 Up Force DTR
2 Up Flow Control &E4
3 Down Result Codes Enabled
4 Down Modem Emulation Disabled
5 Up Auto Answer Enabled
6 Up Maximum Throughput Enabled
7 Up RTS Normal Functions
8 Down Enable Command Mode
9 Down Remote Digital Loopback Test Enabled
10 Up Dial-Up Line Enabled
11 *Up AT Responses Enabled (Extended Responses Disabled)
12 *Down Asynchronous Operation
13 Up 28.8KB Line Speed
14 Up
15 Up CD and DSR Normal Functions
16 Up 2-Wire Leased Line Enabled
* Only switches 11 and 12 are changed from the factory default settings.
Xon/Xoff Modems
Some early modems assume software flow control (Xon/Xoff) between the computer and the modem.
Modems with this design send extra characters during and after the transmitted data. The service
processor cannot accept these extra characters. If your configuration includes such a modem, your
functional results may be unpredictable.
The sample modem configuration files included in this appendix do not support these modems, so custom
configuration files are necessary. Anchor Automation 2400E is an example of such a modem.
If you experience unexplainable performance problems that may be due to Xon/Xoff characters, it is
recommended that you upgrade your modem.
Ring Detection
Most modems produce an interrupt request each time they detect a ring signal. Some modems generate
an interrupt only on the first ring signal that they receive. AT&T DataPort 2001 is an example of such a
modem.
The service processor uses the ring interrupt request to count the number of rings when Ring Indicate
Power-On (RIPO) is enabled. If your modem produces an interrupt on only the first ring, set Ring Indicate
Power-On to start on the first ring. Otherwise, you can choose to start Ring Indicate Power-On on any ring
count.
600 Eserver pSeries 630 Model 6C4 and Model 6E4 Service Guide
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