NDIR Gas Analyzer
Installation 3
Teledyne Analytical Instruments., - Rev. 3
27
The relays are normally tied in to the high limit alarm, low limit
alarm, and failure alarm outputs during assembly. They can be coupled to
other outputs by cutting and installing jumpers on the main board. Consult
the factory for more information on altering the default relay coupled
output.
The relay outputs can be used to switch up to 1 A at 60 VDC or 30
VAC.
3.6.5 Digital I/O Option
The Digital Input/Output option provides opto-isolated digital input
and output capability for controlling functions of the analyzer.
The outputs indicate:
•
The current range in use
•
If a calibration is in progress
• Whether
an
audible
alarm has triggered
•
High and low limit/alarm status
•
Fault alarm status
The inputs are used to:
•
Initiate a zero and/or span calibration
Each output is the collector and emitter of a phototransistor. The
customer must provide a voltage to each collector and a resistor to limit
the current (100 mA maximum per device). The outputs can switch 100
mA at 25 V. See the Option Board Schematic in the Reference Section of
this manual.
The digital inputs supplied by the customer are used to drive LED’s.
The customer must supply a voltage to each LED and a current limiting
resistor. A minimum of 10 mA is required by the LED’s. Do not exceed
20 mA. The forward voltage drop is 1.5V.
The Digital I/O connector mounted on the rear panel of the
instrument is an industry standard metal shell 24 pin ribbon connector.
The contact spacing is 2.16 mm (0.085 in) center to center. The customer
must fabricate the cable and mating connector. One source for the mating
connector is Thomas & Betts Co. P/N 622-24FM.
Table 3-2 shows the pin connections for the connector mounted on
the rear panel. Table 3-3 indicates the logic used in the range selection
and identification.