Hello there. 

I'm assuming your question to be this: 

" Can a person get admission in medical colleges if he/she has got NEET rank 600 and passed from open school with good marks in 12?" 

With a rank of 600 you are sure to get admission in the topmost colleges of the country and your state as well. From colleges like Medical College, Kolkata to Kings Medical College, Lucknow, all would be excellent for a student with a rank of 600. And, passing from open school is completely permissible now for being able to write the NEET examinations, so that wouldn't be an obstacle. With a rank like that, you are all good to go!

Getting a rank of 600 is not easy, and one can surely get admission in very reputable medical colleges with such a high rank. 

If you meant something else in your question, please mention it properly. 

Feel free to post further questions. 

All the best.