Toledo Transducers MoniTTor N269, Инструкция по установке и эксплуатации

Страница: 42 / 53

35
PEAK mode is entered by pressing the "PEAK" key. When pressed, the PEAK LED
will light and the TRACK LED will go out. The PEAK values of the last load cycle will
be displayed in each channel. Peak is the normal operating mode of the N269 meter.
F. CALIBRATION
The N269 meter must be calibrated to display accurate load values generated by the machine.
BEFORE EACH CHANNEL CAN BE CALIIBRATED IT MUST HAVE THE PROPER
CAPACITY ENTERED. If this has not been done yet, refer to the section concerning capacity
in the previous portion of the manual.
Each channel has three adjustments which must be made to calibrate the meter. These are the
BALANCE pot, the GAIN pot, and the LOW-HIGH GAIN switch. There are a number of ways
to calibrate the meter as discussed below. All involve using one precision shunt resistor (1 meg +-
.1%) per channel switched across one leg of each input channel's strain-gage bridge to generate a
reference (calibration) number.
1. PRE-CALIBRATED LOAD CELLS
When a pre-calibrated load cell is the input for a particular channel, the calibration number
has already been determined at the factory. This number is normally included in a spec.
sheet shipped with the load cell. The cal number, however, is dependent upon the value
of the shunt resistor. If the cal number, on the spec sheet is for a shunt different than the
1 MEG shunt used in the N269 a conversion must be made. When the proper number is
determined, the BALANCE and GAIN must be adjusted to read this number on the
channel associated with the load cell.
Put the meter in "TRACK" mode by pressing the "TRACK" key on the keyboard. Be
sure all load cells are properly wired into the channel terminal blocks. Set the LOW-
HIGH GAIN switch to LOW or HIGH as required by the load cell spec. sheet in the
channel being calibrated. Using a small screw driver adjust the BALANCE pots (labeled
"B") so that each channel reads 0 in the display. Turning clockwise causes numbers to
increase.
Now depress the key labeled "SHUNT" on the keyboard. You should see an "S" appear
in the left portion of the channel 0 display. This indicates that the shunt is engaged.
Adjust the GAIN pot (labeled "G") until the calibration number is seen in the channel
display corresponding to that load cell. Depress the shunt key again and the "S" should
disappear from channel 0. Each channel should now display 0. If not, BALANCE the
channel to zero again using the BALANCE pot and then engage the shunt again. Adjust
the GAIN pot if needed to display the proper calibration number again. Dis-engage the
shunt and read 0 in the display.
It is possible that the LOW-HIGH GAIN switch will need to be in a different position for
normal meter operation than it is when setting the calibration number. Check the spec.
sheet and if necessary change the setting of the LOW-HIGH GAIN switch. A normal
operation mode may now be selected.