November 2005
4-6 The Optional Display/User Interface (Option G)
Special Calibration (cont.) 8. Adjusting the Current Loop Hardware at 4 mA
9. Adjusting the Current Loop Hardware at 20 mA
Mode of Operation 10. Input Locking.
Location
in Matrix Description of Function
VH
38
By connecting an ammeter in the loop, the correct cur-
rent (4 mA) can be adjusted by increasing or decreas-
ing the displayed digits.
Note: If the matrix input is locked (VH89), the calibra-
tion values are displayed but the current output is
unaffected. To enable adjustments, VH89 has to be
unlocked by entering “50” into this field.
Location
in Matrix Description of Function
VH
39
Selection of this field assists during calibration, gener-
ating a nominal 20 mA signal, but the actual value
must be 21.92 mA, an over range to a dewpoint of
22°C. By connecting an ammeter in the loop, the cor-
rect current (21.92 mA) can be adjusted by increasing
or decreasing the displayed digits.
Note: If the matrix input is locked (VH89), the calibra-
tion values are displayed but the current output is
unaffected. To enable adjustments, VH89 has to be
unlocked by entering “50” into this field.
Location
in Matrix Description of Function
VH
89
Any number other than “50” will lock the instrument
settings from inadvertent or unauthorized changes.
(The instrument is only unlocked at “50.”)
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