COND SGA-A & SGA-D Manuel_EN Rev3.doc
Page 12 on 20
Rev: 03/08/2006
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When a reduced output is required from a fully loaded transducer, use a less sensitive switch setting.
For an 8 volt output from a fully loaded 2.5mV/V load cell use the 3.19mV/V setting
i.e. (10/8x2.5=3.125mV/V)
Table 3.6 /31 (1.20mV/V SW1 =[0010][000]
The COND SGA/A & COND SGA/D can be calibrated with the transducer connected, provided that two
calibration points can be implemented. e.g. by applying known weights or forces. If this is not possible, a
stable mV source or load cell simulator can be used provided that the precise sensitivity (mV/V) and full range
output (kg) of the transducer is known. In this case the 'Ref (5V/2,5V)' output should be connected to 'strain
input-' and the mV source applied between ‘strain input+’ and ‘strain input-‘.
Actual calibration is carried out in the following way:
1. Set the correct switch settings on SW1 as described above using the transducer's calibration sheet supplied
by the manufacturer. This is normally specified as sensitivity or full range output and should be in mV/V
2. Apply the known low calibration conditions (weight, force or mV/V : this may be zero if required), and note
the analogue output, having ensured that the SW1 settings are correct for the transducer sensitivity as step
1 above.
3. Apply the known high calibration conditions (for optimum accuracy this should be at least 75% of full load)
and note the analogue output.
4. Use the fine trim control, P1, to obtain the required change in Volts or mA, between the two calibration
points (steps 2 and 3). e.g. If the required output at the low calibration point is 0V and the required output at
the high calibration point is 7.5V, adjust P1 in step 4 to produce a change of 7.5V between the calibration
points. Initially, the low calibration point may not produce 0V at the output. If this is the case, note the
reading, e.g. 0.5V, apply the high calibration conditions and trim P1 for the required change in output. i.e.
Trim the output for 0.5 + 7.5 = 8V.
5. Use the fine ‘Zero’ control, P2 in conjunction with the coarse switches SW2/3-8 and polarity switches SW2/1
and 2 to set the output to the required absolute values. Each switch within SW2 offsets the output by a
particular percentage of full scale as shown in Table 3.9.
N.B.: It may be necessary to repeat these steps until the required output is achieved.
4.4.
Calibration Connections using mV Source
Figure 4.1.
