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______________________________________________ Section 3: Operation
8197 Instruction Manual
Page 3-5
3.1.4 RS-232
Com
This is the RS-232 serial communication port. Commands to configure
selectable parameters, output operational status and events, and Test Mode
functions are entered here. Refer to Section 4.2 for a complete description of the
RS-232 commands and responses.
The RS-232 COM connector is a 9-pin series D female. Connector pin
numbering is shown in Figure 3-2. Pin assignments are listed in Table 3-1.
The RS-232 Com port transmits and receives ASCII characters at 9600 baud
structured as 1 start, 8 data, 1 stop, no parity and xon/xoff flow control.
FIGURE 3-2 RS-232 COM PIN NUMBERING
PIN SIGNAL I/O DESCRIPTION
2 RXD O
Receive
Data
3 TXD I
Transmit
Data
5 GND -
Signal
Common
6
DSR
O
Data Set Ready
7
RTS
*
Request to Send
8
CTS
*
Clear to Send
*Pins 7 and 8 are connected together internally.
TABLE 3-1 RS-232 COM PIN ASSIGNMENTS
The RS-232 Com port is configured as data communication equipment (DCE).
Data is output on Pin 2, RXD and commands are input on Pin 3, TXD. When
interfacing to data terminal equipment, DTE, (i.e. a personal computer) a one-to-
one cable is used. Interfacing to a DCE requires reversing Pins 2 and 3 or a null
modem connection. The RS-232 COM port does not require hardware
handshaking. The Request to Send and Clear to Send signals are internally
connected together, and the DSR signal is held high through a pull-up resistor.