Specifications

250
Reference Manual
00809-0100-4026, Rev HA
Appendix C: Advanced configuration
November 2014
Advanced Configuration
C.4.5 Hold off setting
The Hold Off parameter is set to a default value that rarely needs any adjustment (see “Hold off
distance” on page 238 for definition of Hold Off distance). The Process Seal antenna is slightly
more affected by disturbances in the nozzle than the cone and rod antennas. If necessary, a
small Hold Off adjustment may be sufficient to solve the problem.
In a typical situation, a small object, such as a weld joint, may give rise to a disturbing echo. If
this disturbance is strong enough, the transmitter may misinterpret this echo as the product
surface. By setting the Hold Off large enough to avoid a measurement within and close to the
nozzle, the problem is solved, as illustrated below.
The Spectrum Plot function in RRM allows for adjustment to the Hold Off distance:
1. In RRM, click the Spectrum Plot icon
to open the Spectrum Analyzer
window.
2. Select the Configuration Mode tab.
3. Click the Read button and view the
amplitude versus distance graph. If
there is a disturbance caused by an
object in the nozzle, the transmitter
may misinterpret the position of the
surface, as shown to the left. In this
example, the true surface position is
at amplitude peak P3.
4. Move the Hold Off distance line away
from the transmitter i.e. to a position
below the nozzle.
5. Click the Store button.
6. The transmitter will now disregard
any disturbing echoes in the nozzle
and find the product surface.
Hold Off
SPECTRUM ANALYZER
Hold off