SECTION 6
INTERFACING
Analog Outputs
The Model 3345 has 3 analog outputs - one is proportional to the current primary displayed reading - the other
two are buffered electrode potential outputs.
Analog Output Proportional to Displayed Reading
The voltage is proportional to the displayed primary reading. In mV mode there is a direct relationship i.e.
1mV on the display = 1mV from the analog output. In pH mode 1mV = 0.01pH i.e. 7.000pH = 700mV,
2.345pH = 234mV. In concentration mode the user can set the sensitivity of the analog output using the REC
mV menu option. The number entered on the menu option will cause a change of 1mV on the recorder
output. So if REC mV is set to 1E
-3
, and the displayed concentration is 1.00 (1.00E
0
), then the analog output
will be 1.00E
0
/ 1E
-3
= 1000mV.
Buffered Electrode Potential Analog Outputs
Each sensor input has a buffered analog output, which is available on the 25 way D socket.
25 way D Socket
pin 14
sensor 1 buffered output
pin 22
sensor 1 buffered output ground
pin 11
sensor 2 buffered output
pin 18
sensor 2 buffered output
Karl Fischer
A polarised Karl Fischer output is provided. Karl Fischer titrations are enabled by the provision of a 10µA
polarising current output.
RS232
The Model 3345 emulates data communicating equipment, which allows direct connection to the signals of
data terminal equipment, such as personal computers and serial printers.
The Bi-directional RS232 interface is available on the rear panel 25 way D type connector.
The connections are as follows:
TXD 2
- INPUT TO 3345
RXD 3
- OUTPUT FROM 3345
RTS 4
- LINKED TO CTS
CTS 5
- LINKED TO RTS
DSR 6
- OUTPUT FROM 3345
DCD 8
- OUTPUT FROM 3345
DTR 20
- INPUT TO 3345 (must be active)
GND 7
3345/REV A/08-99
40
