Hardy HI 200DNWM DeviceNet Weigh Module - Manual (Page 57)

CHAPTER 8 - TROUBLESHOOTING
8-3
Load Sharing and
Load Sensor
Checkout See Figure 8-2
FIG. 8-2 LOAD SHARING AND LOAD SENSOR CHECKOUT
Load cell wiring is
complete and correct?
1) Does the mV signal increase in a positive direction.
2) If you receive a negative results, check if load cell is
mounted correctly.
a)
The arrow goes with the direction of force.
b) If there isn't an arrow, you must manually verify the
correct direction. A negative reading indicates the
load cell is upside down.
c) Load cells in tension will not reflect a negative
reading if install upside down. If upside down, only
the force applied by the cable would be included in
the weight readings.
d) If you are still receiving a negative signal, verify
load cell wire color code
Multiple load cells?
MAP the mV reading.
Balance the load
1) Verify a positive reading from each load cell, using a
volt meter.
2) Record the mV reading and compare each corner for
proper load sharing.
a)
Proper load sharing should see only a difference
of +/- .5 mV.
b) Larger differences due to motors and piping,
should not exceed +/- 2 mV.
c) If there isn't any motors, valves, or piping to
explain the mV difference, adjust the corners and
balance the mV readings.
d) Use shims, or if equipped adjusting bolts on the
load cell mounting hardware.
e) Drawing a load cell map will help determine the
correct leg to adjust and in which direction.
Three load cells balance like a three legged chair.
1)
Using a sprit level, verify the vessel is vertically and
horizontally correct.
2) Verify if any height change will effect the attitude of adjacent
vessels or piping.
3) Adjust each legs to dynamically match mV outputs
4) Verify the mV readings and physical level when complete.
Four load cells or more present a challenge.
1)
Use volt meter to determine the sum of the load cell signals
and your target mV setting for each load cell.
2) Read the output of individual load cells.
3) Adjust the load cell with the lowest reading to dynamically
match the target mV readings obtained in step 1.
4) Read the mV readings from each load cell to verify a proper
correction.
5) Repeat step 3 and 4 to achieve a proper load sharing vessel.
6) Verify the mV readings and vessel level when complete.