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CHAPTER 5: Operation
5.5 Using the Dual Control Ports (A and B)
The ServSwitch Duo has two control ports, “A” and “B.” Each control port has a
keyboard, mouse, and monitor connection, and either can be used to access the
Switch. Typically port A is used for local access, and port B for remote access from
up to 65 feet (20 m) away. The Switch sends the video image from the selected
CPU to the monitors on both ports, but it will accept keyboard and mouse data
from only one control port at a time. While the other port is active, the Num Lock,
Caps Lock, and Scroll Lock LEDs on the inactive control port’s keyboard will flash,
indicating that the port is currently disabled. Once there has been no keyboard or
mouse data on the active control port for the duration of the “switchover timeout”
period (see Section 4.2.4), the other keyboard and mouse can be used. Once
activity is detected on the second control port, that port becomes the active port
and the first port is disabled. The red status LEDs on the Switch’s front panel (see
Section 5.2) show which port is currently active; if neither the A or B LED is lit,
neither control port is active, so either may be used.
5.6 Things To Keep in Mind About the Keyboards and Mice
PC bootup sequence: When your PCs are powered on, they communicate with any
attached keyboards and mice and load the setup parameters required by their
particular operating systems. It is necessary for the ServSwitch Duo to be attached
and powered on during this sequence so that it can give the PCs the required
responses and keep track of all the modes and settings requested by each of the
connected PCs.
Mouse characteristics: Do not unplug a PS/2 mouse connection from a PC while
the PC is on. Because of the way PS/2 mice communicate, the PC will lose mouse
function and you will have to reboot the PC to regain normal operation.
Unplugging a shared PS/2 mouse from the ServSwitch Duo will have no
immediate effect, but the PC will lose mouse function as soon as you plug the
mouzse back in. (RS-232 mice can usually be freely unplugged and replugged,
provided that one was connected when the operating system initially booted.) The
ServSwitch Duo has a PS/2 mouse-recovery system which allows you to disconnect
and reconnect the shared mouse without powering down the system, but we
recommend using this only when absolutely necessary. See Section 5.10 for details.
Keyboard- and mouse-mode handling during channel switching: The ServSwitch
Duo keeps a log of the keyboard and mouse modes and resolution settings
requested by each of the connected PCs, including the keyboard Num Lock, Caps
Lock, and Scroll Lock states. These settings are automatically restored to the
shared keyboard and mouse when the ServSwitch Duo channel is switched,
ensuring maximum software compatibility.
