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CR10X User Guide
6-8
is taken from these pins. For equipment configured as DTE (see Table 6-3) a
direct ribbon cable connects the computer/terminal to the SC32A. Clear to Send
(CTS) pin 5, Data Set Ready (DSR) pin 6, and Received Line Signal Detect
(RLSD) pin 8 are held high by the SC32A (when the RS232 section is powered)
which should satisfy the hardware handshake requirements of the
computer/terminal.
Table 6-3 lists the most common RS232 configuration for Data Terminal
Equipment.
Table 6-3 DTE Pin Configuration
PIN
=
25-pin connector number
ABR =
Abbreviation for the function name
O
=
Signal out of the terminal to another device
I
=
Signal into the terminal from another device
PIN
ABR
I/O
Function
2
TD
O
Transmitted Data: Data is transmitted from the
terminal on this line.
3
RD
I
Received Data: Data is received by the terminal on
this line.
4
RTS
O
Request to Send: The terminal raises this line to ask a
receiving device if the terminal can transmit data.
5
CTS
I
Clear to Send: The receiving device raises this line to
let the terminal know that the receiving device is ready
to accept data.
20
DTR
O
Data Terminal Ready: The terminal raises this line to
tell the modem to connect itself to the telephone line.
6
DSR
I
Data Set Ready: The modem raises this line to tell the
terminal that the modem is connected to the phone
line.
8
DCD
I
Data Carrier Detect: The modem raises this line to tell
the terminal that the modem is receiving a valid carrier
signal from the phone line.
22
RI
I
Ring Indicator: The modem raises this line to tell the
terminal that the phone is ringing.
7
SG
Signal Ground: Voltages are measured relative to this
point.
If the computer/terminal is configured as DCE equipment (pin 2 is an input for
RD), a null modem cable is required. (Refer to the SC32A manual for details.)
Alternatively, the SC932 can be used in place of the SC32A and a null modem.
6.6.3 Communication Protocol and Trouble Shooting
The ASCII standard defines an alphabet consisting of 128 different characters
where each character corresponds to a number, letter, symbol or control code.