18
PMC423* Port Serial, Front/Rear I/O
Publication No. RX-URMH 006 Rev. E.0
2 •
Theory of Operation
This chapter provides information for local device connections, the bridge to the host
PCI and the general system's function. The design of the PMC423 is illustrated in the
block diagram that follows.
2.1 PMC423 Block Diagram
Figure 2-1 PMC423 Block Diagram
The PMC423 can operate with the 32-bit 33/66-MHz PCI bus, +3.3 V or +5 V PCI
signaling. This allows for the maximum flexibility for the different PCI bus speeds
and signaling. The signaling level for the serial communication (RS232, RS422, etc.) is
configured via the software. The card generates the necessary voltage for the serial
signaling onboard using the +5 V supply. This allows the PMC423 to operate from
the +3.3 V and +5 V supply only.
There are two eight-port serial devices that are after the PCI to PCI bridge for a total
of sixteen ports. Due to the density of the serial ports, the hardware handshake
signals have not been routed to the front or the rear of the card.
PCI/PCI Bridge
Host PCI
8 Port Seria l
L
Lo
oc
ca
all P
PC
CII B
Bu
us
s
Sign al
8 Port Serial
Signal
Signal
Condi tion ing
Signal
1
Port
2
3
4
5
6
16
15
14
13
7
8
9
10
11
12
Port
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