NI DAQ USB 6221 and EM1 optical encoders

Hi,

i connect my NI DAQ USB 6221 device with EM1 optical encoder. i wrote a function in MATLAB that control and get data from EM1 optical encoder through NI DAQ device. My problem is that, values from the encoder comes to me with some delay. I am using SESSION based interface in order to connect with the encoder.

Is there any suggestions to eliminate the delay and get real time data.

Thank you a lot.