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SERVSWITCH™ AND SERVSWITCH ULTRA™
4.3.10 S
ET
U
NITS
(IBM
AND
M
ULTIPLATFORM
M
ODELS
O
NLY
)
Use this command to tell a
n IBM only or multiplatform
ServSwitch master
how
many submasters (as opposed to CPUs) are directly attached to it. It doesn’t
matter what kind of Serv device the submaster is. For example, if you were to
take an 8-port ServSwitch and directly attach three other ServSwitches, a
Matrix ServSwitch, a ServManager, and two CPUs, the master ServSwitch
would have five submasters on it, so you would set Units to 5.
CAUTION!
We strongly recommend that you do not attach submasters of different
Serv types to a master ServSwitch. If you must do so, make sure that all
of the CPUs attached to each such submaster use the same type of
keyboard and mouse input.
ServSwitches use the Units value to find CPU ports. If you select a CPU that is
directly attached to the ServSwitch, the Switch can simply switch to that CPU port.
However, if you select a CPU attached to a submaster, the ServSwitch has to switch
to the submaster’s port and issue switching commands to the submaster. The Units
setting is the only way it knows where, for example, CPU 18 is, and how to go about
accessing that port.
Figure 4-2 on the next page shows a typical pair of alternatives that the
ServSwitch can’t resolve properly unless Units is set correctly. The ServSwitch in
the diagram can’t tell merely from its hardware connections how many submasters
it is attached to. Without a number for Units—even assuming that Width is set
correctly to 4—if you were to select CPU 7 on that Switch, it would not know
whether CPU 7 was attached to a submaster on port 2 or directly attached on
port 4. With Units, the ServSwitch knows to switch to port 4 if Units is 1 or to switch
to port 2 and send the “switch to port 3” command if Units is 2.
The default value for Units is 0. To set Units for a ServSwitch (which you may do
at any time), press and release the left Control key, type [U] followed by the
number of submasters (from 1 to 3 digits), and press [ENTER]. Enter the Keep
Settings command after you enter this command. Units can be set to any value
from 0 to 255, but Units values higher than the number of ports on your
ServSwitch (allowed in order to support future expansion capabilities) might cause
the ServSwitch to behave unpredictably.
Please note that if you are sharing Matrix ServSwitch submasters between two
ServSwitch masters in your system, and especially if you have submasters of other
types attached to one or both of the masters, the Units value might have to be set
differently for each master.
If you are having difficulty switching between ports or scanning, and one or
more of your CPUs are receiving spurious data, check the Units setting of the
ServSwitch you are using; you are probably seeing misdirected switching
commands that the Switch thinks it is sending to submasters.