CAN you please help me on how to define the print mark sensor .. for example the sensor is I0.0 where in the program should i use this input as print mark sensor

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Split from SIMATIC S7-1500T RotaryKnife - Knife waits forever for the first cut.

Hello,
To connect a print mark sensor to the application, you need to have a “measuring input” technology object.
For this, see following SIOS entry:
https://support.industry.siemens.com/cs/ww/en/view/109974351
Documentation chapter 4 and 5

Afterwards the technology object “measuring input” can be connected to the application, as shown in documentation 
or example project.

If you have further questions to the application, please write us directly on our team e-mail adress:
printing.converting.team.automation@siemens.com

As you can see, there are people that are willing and able to help you. But to be fair to the volunteers, I do suggest that you make mention of which equipment you are using. When you speak of “I0.0”, I may think that you are using the motion control facility built into an S7-1200. Others may think you have a Sinamics based motion controller.

i have packaging machine that uses rotary knifes , and there is a sensor that reads the cut(print) mark on the material and gives me a digital feed back as digital input on my plc .. and when i try to add measuring input in the TO of the knife i cannot find any option that can use digital input 

ahmad essam

i have packaging machine that uses rotary knifes , and there is a sensor that reads the cut(print) mark on the material and gives me a digital feed back as digital input on my plc .. and when i try to add measuring input in the TO of the knife i cannot find any option that can use digital input 

 I guess it is a state secret since you are making it impossible for any volunteer to help you. You make no mention of which Siemens equipment is used. 

In that case.. Contact the original manufacturer or a Siemens representative to make a site visit so that they can see for themselves what your needs are.