HP Remote Assistant Card - Manual (Page 48)

2 Hardware Installation and Configuration
30
Configuring a Null Modem Cable
In a direct connection, the null modem cable has key signals crossed to make the
terminal appear as if it were a modem. The figure below illustrates the cable
configuration required for making a direct connection to the HP Remote Assistant.
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Terminal or PC HP Remote Assistant
EISA Card
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI 1
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GND
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CTS
RI
Male Male Female Female
Figure 2-16. Null Modem Cable Configuration
It is possible to create a minimal three-wire direct connection using the cable
configuration illustrated in the figure below.
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Terminal or PC HP Remote Assistant
EISA Card
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI 1
2
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8
9 1
2
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9 DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI
Male Male Female Female
Figure 2-17. Minimal Null Modem Cable Configuration
When the HP Remote Assistant enables its port by asserting DTR, it automatically
recognizes that DCD, DSR, and CTS are asserted and establishes the connection.