51-638 Echotel Model 338 Two-Wire Ultrasonic Transmitter
18
P26: (m/hr) Vessel fill rate
Factory default value for P26 is: 2000 m/hr
(6562 ft/hr).
P27: (m/hr) Vessel drain rate
Factory default value for
P27 is: 2000 m/hr (6562 ft/hr).
Parameters P26 & P27 can be used to set the rate of filling
or draining a vessel. Typical values for P26 & P27 are any-
where from 60 m/hr (200 ft/hr) to 2000 m/hr (6562
ft/hr). Entering fill and drain rate values can also provide
additional protection against echo loss in applications
involving vapors or turbulence. It is extremely important
that the values of P26 & P27 not be smaller (slower) than
the fastest possible filling/emptying rate of the specific
application, or the ultrasonic signal will be lost.
P28 - - - a Echo loss error reporting
Factory default value for P28 is: 0
Echo loss error
a
reporting mode
Conditions
0
Delayed
Initially, the delayed mode will hold
the display and 4-20 mA output at
their last value during an echo loss. If
the echo loss continues for a period
of time 10 seconds longer than twice
the damping set in
P20
, then the dis-
play will change to "no ECHO" and
the 4-20 mA output will change
according to the "Error Indication
Mode" set in
P12.
1
None
The display and 4-20 mA output
hold their last value until the echo
loss clears and a valid echo is received
by the 338.
2
Advance to full
If an echo loss occurs while the vessel
is filling, the display and 4-20 mA
value change to indicate a full vessel
as configured in
P04
and
P05
. The
full vessel is indicated at the fill rate
as preset in
P26.
3
Immediate
During an echo loss, the display will
immediately change to "no ECHO"
and the 4-20 mA will change accord-
ing to the "Fault Value" preset in
P12
.
4
Empty Tank
An echo loss may occur in completely
indication
empty vessels with a spherical or coni-
cal bottom due to deflection of the
ultrasonic signal. If the echo is lost
when the vessel is completely empty,
the display and 4-20 mA will immedi-
ately change to indicate an empty vessel.
