DOSAGE
38
therefore the instrument gives the possibility to load the silo and then to unload the desired
quantity from it:
-
To obtain a dosage of this type, one should enter an unloading activity as first activity of the formula,
or a single component formula made up of a single unloading activity, with a target greater than 0
-
By entering an unloading activity with target equal to 0, one obtains a total unloading (see first
unloading method). By entering an unloading activity after another activity, one obtains a split
unloading (see second unloading method).
-
Once the dosage is started, the instrument checks if the weight is sufficient to execute the partial
unloading: if the weight is lower than the TOTAL UNLOADING END + ACTIVITY TARGET threshold the
“INSUFFICIENT WEIGHT” error message will appear; one exits the error status by pressing for an
instant the external INPUT 1 or the START button, once the weight is greater than the required one.
-
The instrument zeroes the weight on the scale and enables the fast dosage output and the product
one: the dosage starts at the maximum speed.
-
When the weight reaches the TARGET TO BE DOSED - SLOW DOSAGE WEIGHT - MATERIAL WEIGHT
IN FLIGHT threshold, the approximate dosage output disables and the dosage continues in fine
mode.
-
The dosage ends, with subsequent disabling of the output relative to the linked output, in the
moment in which the TARGET minus the MATERIAL WEIGHT IN FLIGHT is reached.
-
After this a wait time starts equal to the TIME FOR MATERIAL FALLING DOWN (
) in which one
presumes that material still falls on the scale and the TARGET is reached.
-
Once the wait time is finished:
-
If the instrument is enabled, the check on the dosed weight starts: if the weight of the dosed
material is not within the set tolerance, the "TOLERANCE ERROR" error is signalled, and the error
output (default = OUT3) is enabled.
-
Now the operator can remove the exceeding weight or add the missing weight; in this phase it is
possible to use the message which appears (WEIGH OK if within the tolerance, or TOLERANCE
ERROR if out of tolerance).
-
By pressing for an instant the external INPUT 1 or the START button, one exits the error status: the
weight now present will be considered valid and therefore accumulated in the formula production
and in the general total.
-
The data of the executed dosage is automatically stored and transmitted through the serial line for
the printing or the storage on PC/PLC.
-
A wait time starts equal to the DATA READING TIME (
) in order to allow the reading of the
activity data; the instrument waits for this time before passing to the following phase.
b) Enabling unloading phase
R1 and R2 relay (dosage and speed relays) are enabled: the process then starts at maximum speed.
The status bar message on the display is:
1)
FAST UNLOADING:
indicates that the material is being dosed at the maximum speed; this remains
until a weight value is reached in which the
SLOW FLIGHT WEIGHT
is missing from the
FINAL WEIGHT.
2)
At this point the
SLOW UNLOADING
is displayed indicating the end of the fast dosage and the
beginning of the slow dosage.
3)
When the weight reaches the TARGET (or WEIGHT TO BE DOSED) – THE FLIGHT WEIGHT, the
message
WAIT STABLE WEIGHT
is displayed.
