VEGA WEIGHTRAC 31 4 … 20 mA_HART - four-wire - Manual (Page 49)

49
7 Setup with PACTware
WEIGHTRAC 31 • 4 … 20 mA/HART - four-wire
42374-EN-131119
In a last step, complete the adjustment with the setup assistant. After
terminating the assistant, the program jumps back to the usual DTM
program environment.
Information:
After a successful run of the setup assistant, you have to adjust two
points in the DTM.
Adjustment
Fig. 34: Determine zero rate (tare measurement)
To increase accuracy, you have to carry out the zero rate determina-
tion with an empty conveyor belt. During the zero rate determination
make sure that no material is transported and that no residues fall
onto the conveyor belt. In such case, you have to repeat the proce-
dure.
The conveyor belt should make several circulations to compensate for
irregularities of the conveyor belt or the conveyor system. The more
often the conveyor belt circulates during the zero rate determination,
the more precise the zero rate determination will be.
Tip:
To check the zero rate determination (taring), you can carry out a test
measurement after the adjustment with empty belt over a period of
5 to 10 minutes. If no or only a negligible feed rate sums up during
the measurement, the zero rate determination has been carried out
correctly.
1. Start empty conveyor belt and let it run idle
Tip: Mark the conveyor belt with coloured adhesive tape
2. Set the source container to "ON"
3. Click the button "Determine zero rate"
4. Let the conveyor belt run for two to three belt lengths
5. Terminate the zero rate determination
6. Stop conveyor belt
The determined value of the zero rate is transferred to the sensor
Note:
In case of heavy belt wear, this zero rate determination should be car-
ried out regularly to keep the accuracy constant.
Complete
Adjustment/Zero rate
determination (DTM)