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Principle of Operation

 
For correct operation the amplifier output must be zeroed and calibrated to remove the dead weight (zero or tare). 
During this operation the microprocessor will negate the effects of the dead weight to provide a zero reference value. On completion the amplifier will indicate 0V when no web is present.
 
The next stage is to place a load onto the sensing roller according to the MAXIMUM tension required. Please note that the sensing roller load must follow the production web path.
The amplifier will adjust automatically to give an output voltage on the appropriate channel(s) that will be equal to 10V at full scale (MAXIMUM).
 
If the MAXIMUM load is not available then a proportional calibration will be used to replicate the full load.
If full loading is not possible then the proportional mode must be selected and a reference voltage scaled proportionally to this load is created before calibration can proceed. The appropriate output channel(s) will then assume this voltage whereby the full scale output will be equal to 10V.
 
Changing the measuring range without recalibration or different load cells
 
If different materials with different tensions are used the measuring range of the amplifier can be increased without the need to re-calibrate and making use of the same load cell rating. The switching between the ranges is carried out by the active low digital inputs. With this method it is possible to adjust the signal output to provide 0…10V proportional to 25%, 50% or 75% of the actual calibrated load. 
 
Connecting the Transducers
 
When interfacing the transducers the following points should be taken into account.
 
·     The convention adopted here is that when using with TTS transducers these should be orientated such that the red spot is positioned away from the web angle bisector as shown in the following diagrams.
 
If the wiring is incorrect the amplifier may fail to calibrate successfully to give the 0…10V output.
 
It is a straightforward procedure to establish that the amplifier is correctly wired.
 
1.     Connect a meter to load cell signal terminals. Check channels A and B. Meter positive should be on Sig + and meter negative on Sig – of the transducer.
2.     Note the no load voltage and observe the polarity.
3.     Load the sensing roll and note the output voltage again and observe the polarity.
4.     Calculate the difference between the No load and Loaded voltage (in millivolts).
5.     If the load cell is correctly wired when increasing the load the resultant signal should be positive going i.e. if the off set voltage is minus 7 millivolts on the no load condition and the resultant voltage with load is minus 3 millivolts this would indicate that the transducer and the wiring are correctly orientated.