Encoder and PLC

Hi there. I have connected my rotary encoder (E6B2-CWZ5B) with PLC (LM 3106A). I connected output A and output B to PLC. I can read inputs in CoDeSys. But i need to read steps and distinguish clockwise/counterclockwise steps. Any help?

two channels A and B being shifted 90 degree out of phase.most is A than B 90 in CW (viewed from the shaft.)
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