Teledyne API Model 200AH NOX Analyzer Instruction Manual, 06492, Rev. G2
7-10

7.5. Use of Zero/Span Valves with Remote Contact

Closure
The Zero/Span valve option can be operated using Remote Contact Closures provided on the rear
panel. See Figure 2-2 for connector location and pinout. There are 3 sets of contacts on the rear
panel. They operate the zero valve, LO span valve, and HI span valve. To operate the valves,
they must be held closed for at least 1 second. The valve will remain in operation for as long as
the contacts are closed. In order to operate the valves again, the contact closures should be held
open for at least 1 second, then may be closed again.
The default action is to do a span check when the valves are operated. A span check does not
calibrate the instrument when the valves are operated. To calibrate the M200AH when the valves
are operated, go to the VARS section on the front panel menus. Press SETUP-MORE-VARS,
then scroll to DYN_ZERO.
DYN_LO_SPAN or DYN_HIGH_SPAN, and set the variable to ON. With the variable in the
ON state, the M200AH will calibrate when the contact closure is released.
Table 7-9 shows what type of check is performed based on the settings of the three contact
closures.
Table 7-9: Z/S Valve Modes with Remote Contact Closure
External Zero
Contact Closure External LO Span
Contact Closure External HI Span
Contact Closure Operation
Open Open Open State when in SAMPLE mode,
normal monitoring.
Open Closed Open Low Span check or calibrate*
Open Open Closed High Span check or calibrate*
Closed Open Open Zero check or calibrate*
*Calibrate only if Dynamic Calibration Variable is ON