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3-wire interface
Interface settings The baud rate, stop bits, parity, protocol, and data bits must be configured
Data bits
The switch uses a 3-wire RS-232 interface. It provides a simple connection
between devices because you can ignore hardware handshake requirements.
The switch uses the following connections on its RS-232 interface for 3-wire
communication:
SGND (Signal Ground)
TD (Transmit Data from switch)
RD (Receive Data into switch)
The TD (Transmit Data) line from the switch must connect to the RD
(Receive Data) line on the controller. Likewise, the RD line from the switch
must connect to the TD line on the controller. The RS-232 interface on the
switch ignores all signals on the DCD, DSR, RTS, and CTS lines.
NOTE
If the instrument is used with QBASIC programming language, pin 6, 7, and 8 of the DTE
connector should be shorted together.
exactly the same for both the controller and the switch to properly communi-
cate over the RS-232 interface. The RS-232 interface capabilities of the light-
wave switch are listed below:
Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1200 or 9600
Parity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . None
Data Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Stop Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The baud rate is factory set to 9600 baud. To change the baud rate, press the
LOCAL key twice. The current baud rate is displayed. Use the arrow keys to
change the baud rate to 1200 or 9600. When the desired rate is displayed,
press ENTER.
Data bits are the number of bits sent and received per character that repre-
sent the binary code of that character.
Programming
Programming over RS-232
Switch
Computer
Pin 5
Pin 5
Pin 2
Pin 2
Pin 3
Pin 3
4-9
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