3KP64 - 5.5
3000PLUS WITH 5D64 INSTRUCTION MANUAL V. SB.2
Daytronic Corporation
2211 Arbor Blvd. Dayton, OH 45439 • (800) 668-4745
Tel: (937) 293-2566 • Fax: (937) 293-2586 • www.daytronic.com
There are three ways to instruct the 3000PLUS instru-
ment to instantly “freeze” its “auxiliary” DAC and “raw
volts” outputs (Channels 2 and 3) at their existing read-
ings—and to subsequently “unfreeze” these outputs to
resume normal measurement reporting*:
VIA LOGIC INPUT
See Section 2.E for an explanation of how the
3000PLUS instrument’s rear-panel
HOLD (“HLD”) logic
input can be connected for application of the signal
hold, either by switch closure (no external supply
required) or by active TTL logic.
VIA CONFIGURATOR SOFTWARE
You can use the HOLD ON/OFF button of the “Live”
Output
window (when Channel 2 or 3 is on display) to
apply and remove the signal hold. See Fig. 11 and
“Applying a Hold Command to the ‘Auxiliary’ and
Voltage Outputs”
in the Configurator ON-LINE HELP.
VIA OTHER SOFTWARE COMMAND SOURCE
When communicating with the 3000PLUS through a
conventional or customized “terminal emulation” pro-
gram (see Section 5.A, above), you can apply the signal
hold by issuing a
HOLD (HLD) command of the form
HLD = ON
To discontinue the signal hold, command
HLD = OFF
On receipt of either of the above HLD commands, the
3000PLUS will respond with “ACK.” These are strictly
run-time “imperative” commands; the 3000PLUS will
always power up in the
HLD = OFF state.
INTERROGATING FOR HOLD STATUS
Every time the “Live” Output window is opened, the
Configurator will automatically interrogate for the
3000PLUS meter’s current hold status, which will then
be reflected in the state of the
HOLD ON/OFF button
(see above).
When communicating with the 3000PLUS through a
conventional or customized “terminal emulation” pro-
gram, you can request the hold status by sending the
“read” form of the
HOLD (HLD) command:
HLD
The meter will answer with “ON” (if Channels 2 and 3
are currently frozen) or “OFF” (if they are not).
5. OPERATING CONSIDERATIONS
5.C APPLYING A SIGNAL HOLD
* Like captured peaks and valleys, signal values frozen in
response to a
HOLD (HLD) command are subject to the cur-
rently effective
decay rate of the “auxiliary” DAC output (for user
adjustment of the “leak rate,” see Section 5.B, above).
By specifying a TARE OFFSET for the 3000PLUS instru-
ment’s “auxiliary” DAC output (Channel 2), you can
automatically subtract out the container weight in batch-
weighing operations or establish an arbitrary zero refer-
ence in comparator gaging operations (among many
other applications).*
The actual application of a tare offset value to Channel
2 is initiated solely by means of a logic input at the rear
TARE (“TAR”) screw terminal shown in Fig. 2. See Sec-
tion 2.E for an explanation of how the “TAR” logic input
can be connected for the tare enable/disable, either by
switch closure (no external supply required) or by
active TTL logic.
The
amount of offset to be algebraically subtracted
from Channel 2 is determined by the last-entered
DESIRED TARED OUTPUT (“TAR”) value, a number
stored in EEPROM by the 3000PLUS instrument.
Expressed in the active engineering units, the currently
effective TAR value indicates
the reading to which
Channel 2 is to be forced when tare is next enabled
.**
Fig. 20, below, shows how this works. Here, tare is initi-
ated at time t
1
—and maintained until time t
2
—by a con-
tinuously “true” logic
TARE input. At t
1
, the “auxiliary”
output is brought down to the last-entered TAR value.
From this point, it continues to track Channel 1, but now
with the continuous application of the constant tare off-
set determined by the difference between the value of
Channel 1 at time t
1
and the stored TAR value. At time
t
2
, tare is disabled by resetting the TARE input to Logic
0
, and Channel 2 is returned to the “untared” tracking of
Channel 1.
(cont’d)
5.D APPLYING A TARE OFFSET
* The tare offset should not be confused with the DISPLAY
OFFSET (DSO)
, discussed in Section 1.D, which is a user-
specified amount of ± offset applied to the instrument’s scaled
measurement display in addition to any zero offset resulting
from instrument calibration and to any currently enabled tare
offset. See Sections 3.B and 4 for entering the desired DSO.
** In many cases, it is desirable to keep the default TAR setting of
“0,” so that tare can be enabled
while only the container itself is
being weighed
, thereby resulting in an initial “empty” reading of
exactly zero.
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