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Getting StartedTeledyne API – Model T300/T300M CO Analyzer
Teledyne Analytical Instruments 48
3.3.1.5. CONNECTING THE STATUS OUTPUTS
The status outputs report analyzer conditions via optically isolated NPN transistors,
which sink up to 50 mA of DC current. These outputs can be used interface with
devices that accept logic-level digital inputs, such as Programmable Logic Controllers
(PLCs). Each status bit is an open collector output that can withstand up to 40 VDC.
All of the emitters of these transistors are tied together and available at D.
ATTENTION
COULD DAMAGE INSTRUMENT AND VOID WARRANTY
Most PLC’s have internal provisions for limiting the current that the input
will draw from an external device. When connecting to a unit that does
not have this feature, an external dropping resistor must be used to limit
the current through the transistor output to less than 50 mA. At 50 mA, the
transistor will drop approximately 1.2V from its collector to emitter.
The status outputs are accessed via a 12-pin connector on the analyzer’s rear panel
labeled STATUS (see Figure 3-4). Pin-outs for this connector are:
STATUS
1 2 3 4 5 6 7 8 D
+
SYSTEM OK
HIGH RANGE
CONC VALID
ZERO CAL
SPAN CAL
DIAG MODE
Optional O
2
CAL
+5V to external device
Figure 3-11: Status Output Connector