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C578M-A (4/05) 11
This allows users with existing RS-232 DT devices to retain that configuration capability in the new
HS. Figure 1-6 highlights the geometry of this hookup.
Additional DTs of the same type must be connected to CC1 Sercom ports (via SEU output ports of the
HS) and require RS-232 to -422 converters.
Figure 1-6. COM 2 Port Options
A couple of working rules with respect to diagnostic tool availability are in order here. During default
operation (see Figures 2-4 and Figure 2-5) diagnostic tools attached to EQUIPMENT output ports
“follow” the switch in control. Under these conditions, the following results can be expected when the
described operation is performed:
1. You can view, at will, the diagnostic activity for either switch (Master or Slave) regardless of the
operational mode (including default) as long as that switch is online. This is done by pressing the
KVD (Keyboard, Video, Data) A (or B) button located on the front panel of the CM9760-CCC for
the A- or B-side diagnostic view you want to see (see Table B, Front Panel Button Operation).
When the KVD button is pressed, you will view the devices connected to the AT KBD, and VGA
port connections for the side (A or B), (Master or Slave) that you selected. It is important to note
that the PRINTER, COM 1, and COM 2 ports do not follow KVD activity under any circumstances.
2. If the diagnostic view is switched manually via the KVD button, as in (1), it remains there until
(a) the operator manually switches back to the opposite side, or until
(b) the system forces a change due to a system fault. A system fault may or may not result in a
return to the original diagnostic view. That depends on which switch becomes the desig-
nated Master when the changeover, if deemed necessary, occurs. This is determined by
the HS itself. It occurs automatically as the result of configuration settings and is not under
user control.
3. Any system change (as noted in 2b) co-opts any existing diagnostic view and any resulting
change occurs under the control of the HS and not the operator. Moreover, the HS controls and
automatically transfers ALL ports (including COM 1 and COM 2) to the control of the designated
Master in the event of a system failure.
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