Teledyne 300M instruction manual least, to be established

Teledyne API Model 300M CO Analyzer Instruction Manual, 04033, Rev. A

3.6Remote Zero/Span Check or Adjustment (Contact Closure)

In addition to adjustment via the front panel buttons, the analyzer can be adjusted by means of two contact closures called EXT_ZERO_CAL and EXT_SPAN_CAL. (See Figure 1-3for the location of the terminals for connection of the contacts on the rear panel.) The CPU monitors these two contact closures every 1 second and looks for a positive transition (i.e. 0 → 1) on either signal. If a positive transition occurs on EXT_ZERO_CAL, the CPU will perform a zero check. If a positive transition occurs on EXT_SPAN_CAL, the CPU will perform a span check. When a negative transition i.e. 1 → 0) is detected, the CPU will go into hold-off.

Also, if a positive transition occurs on either signal while the M300M is in zero, span check or hold off, it will immediately switch to the specified mode. For example, if the analyzer is in zero check and a positive transition is detected on EXT_SPAN_CAL, then the instrument will immediately go into span check. To perform a zero check followed by a span check, first generate a positive transition on EXT_ZERO_CAL, and then when you want to do the span check, generate a positive transition on EXT_SPAN_CAL.

The remote calibration signals may be activated in any sequence, providing a virtually unlimited number of calibration types.

Remote adjustment is similar to automatic Z/S checking in that if dynamic calibration is enabled, the internal CO formulas will be modified following calibration. To enable or disable adjustment, press SETUP-MORE-VARSand press NEXT until the variable DYN_ZERO or DYN_SPAN is displayed. To change the setting, toggle the value between OFF - ON and press ENTR to store the new value or EXIT to leave the value unchanged.

NOTE

Teledyne API recommends that contact closures remain closed at

least

10 minutes to allow for an accurate average zero or span value

to be established.

NOTE

Remote zero and span adjustment alter the formulas used to compute the carbon monoxide readings if DYN ZERO or DYN SPAN are enabled.

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