4. Measuring Thickness
DMS 2 Operating Manual Page 111
Step 4:
Press below the selection titled LAST R. You’ll
note that the following two options are available:
• HOLD—The thickness value will continue to be
displayed, but it’s appearance will change to “hollow”
lettering, when the probe is uncoupled.
• BLANK—The thickness value won’t be displayed when
the probe is uncoupled. Instead, a row a dashes will be
displayed.
Step 5:
The uncoupled thickness display will be set to the
configuration last chosen, until the next time the instrument
is powered on or a P-set is stored.
NOTE:
Each time the instrument is powered on or a P-set is
stored, the LAST R setting will revert to the default of HOLD.
4.4 Adjusting the A-scan Display
When properly set up, the A-scan display shows the sound
wave (or echo) signals that are used to determine the
thickness measurement. This section describes the various
ways in which the A-scan display can be modified.
Note that the DMS 2 is designed to automatically configure
the A-scan display based on information collected during the
calibration and probe-zeroing processes. (Refer to Sections
3.3.3 and 3.3.4.) Most users will find that the A-scan display
won’t need to be adjusted in most applications. In fact, it’s
typical that the operator will lock the instrument following
initial calibration and A-scan adjustment. This prevents
unintentional changes to A-scan configuration. See Section
3.3.5 to lock and unlock the instrument.
Failure to properly perform calibration and probe zeroing
procedures, or poor probe-to-material coupling may result in
the continued need to adjust the A-scan display.
NOTE:
In DUAL and SIP modes, all measurements are
made to the flank of the triggered echo; that is, the intersec-
tion of the leading (left) edge of the echo signal and the gate
bar. In D-MULTI and S-PEAK modes, measurements are
made between the peaks of the two triggered backwall
echoes. Peak measurement isn’t affected by the amplitude
and shape of the echoes. In S-FLANK mode, measurements
are made between the flanks of the two triggered backwall
echoes.
4.4.1 How the A-scan Display can be Modified
The appearance of the A-scan display can be modified to
improve visibility, adjust for differences in individual signals,
and to match operator preference. Normally, the A-scan
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