Teledyne API Model 200A NOX Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
9.3.4.3 Status Output Lines, External Contact Closures
The Status lines consist of 2 active input lines, and 12 active output lines. Additional circuits are
present on the board but currently unused. Individual lines are set or cleared under CPU control
depending on the assigned alarm condition. The CPU also monitors the 2 input lines for remote
calibration commands. The status inputs and outputs are terminated at the rear panel, see the
Connector Board schematic in the Appendix.
The output lines are opto-coupled NPN transistors which can sink 50 ma max of current with a
voltage of 30 VDC max.
The input lines are optically coupled with inputs pulled up to +5 VDC. External contacts can be
contact closures or open collector transistor contacts. DO NOT apply any voltage, since +5 VDC
is supplied internally.
Individual status lines can be set or cleared using the DIAGNOSTIC mode SIGNAL I/O. This
can be useful for simulating fault conditions in the analyzer to see if external circuitry is working
correctly. See Table 5-5-10 for pin assignments.
9.3.4.4 4-20 mA Current Output
4-20 mA current loop option replaces the voltage output of the instrument with an isolated 4-20
mA current output. The current outputs come out on the same terminals that were used for
voltage outputs, see Table 2-2-2. It is programmable for 4-20mA or 0-20mA and has a 1500 V
common mode voltage isolation and 240 V RMS normal mode voltage protection.
Vloop = 28V max which is sufficient to drive up to a 1000 ohm load.
9.3.5 Power Supply Module
The Power Supply Module consists of several subassemblies described in Table 9-9-13.
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