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7
Digital Communication Interface
This instrument is capable of communicating with and being controlled by other
equipment through the digital serial interface.
With a digital interface, the instrument may be connected to a computer or other
equipment. This allows the user to set the set-point temperature, monitor the tempera-
ture, and access any of the other controller functions, all using remote communications
equipment. Communications commands are summarized in Table 4 on next page.
7.1
RS-232 Connection
The three-conductor jack for the serial port is located on the back of the instrument.
One serial cable is included. Additional or longer cables, of three meters or less, can
be constructed by following the wiring diagram shown in Figure 5 on this page. 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.
GND
RxD
TxD
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 instrument from a computer. A full list of commands follows in
Section 7.2, Interface Commands, on page 32.
Commands sent to the instrument 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 instrument end with a carriage
return. If the linefeed setting is on, a linefeed is also sent after the carriage return.
GND
5
9
4
8
TxD
3
7
RxD
2
6
1
Digital Communication Interface
RS-232 Connection
31
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