Dry-well Calibrator
Digital Communication Interface
21
RS-232 Connection
The three-conductor jack for the serial port is located on the back of the Product. One serial cable is
included. Additional or longer cables, of 3 m or less, can be constructed by following the wiring diagram
shown in Figure
.
Note
The TxD line on one side connects to the RxD line on the other and vice-versa. To reduce the
possibility of electrical interference, the serial cable should be shielded with low resistance
between the connector and the shield and should not be much longer than is necessary. The
protocol for serial communications is 8 data bits, 1 stop bit, and no parity. Use no flow control.
Set the linefeed to ON (all carriage returns are followed by a linefeed (LF, ASCII 10)), and the
duplex to HALF, disabling echo.
Figure 5. Serial Cable Wiring
The serial port can be used to transmit measurements to a computer or printer or to change settings of
the Product from a computer. A full list of commands is in
Commands sent to the Product must end with an EOS character which is a carriage return (CR, ASCII
13) or linefeed character (LF, ASCII 10). Commands can be sent with upper or lower case letters. Data
returned from the Product end with a carriage return. If the linefeed setting is on, a linefeed is also sent
after the carriage return.
1
2
3
4
5
6
7
8
9
RxD
TxD
GND
RxD
TxD
GND
