Calibration is the comparison of measurement values of your transducer with those of a calibration standard at specified conditions. For this procedure you will need to use the local diplay of the transducer or a remote software provided by the vendor of the transducer. A data acquisition system will not support you for this task.
Or do you like to know, how to connect and configure the transducer, to get its values diplayed?
As Arne correctly said, it is a calibration by comparison and you have to have a reference detector or a reference pressure values generator in order to calibrate your device under test (DUT).
The final outcome of your exercise is a two column table stating the 'reference' pressure value vs DUT pressure readings and, eventually, a third correction column, stating the correction to be applied to your DUT.
The calibration conditions, procedure and complexity may vary according to the pressure value span, the required uncertainty, the final use of your DUT, etc, etc.
The data acquisition system acts as an 'interface' introducing its own uncertainty to the final one. Therefore the data acquisition system should be calibrated during the pressure transducer calibration.
I am done with the connection and configuration of the transducers to the DAS, what I am looking for as of now is the calibration of those pressure transducers in the DAS using Benchlogger 3 software.
actually, I do not see the need to calibrate the transducer to the DAS. Calibration is the process to validate (and sometimes adjust) the measurement equipment. But there is no measurement between transducer and DAS. An exception would be, if there is analog signal transmission between transducer and DAS (for example by a 4..20 mA signal, in this case a calibration of the current input of the DAS is suitable). But for sure you would use digital signal tramsmission (probably Ethernet based) without the need of calibration. Thus the only tasks that I see are scaling, perhaps linearization, but no calibration.