i would firstly tell you that PSG Collegeof Technology, Coimbatore is one of the top private college located in Tamil nadu and does not take admission  through JEE MAINS .
PSG College of Technology is a autonomous college affiliated to Anna University. Admission to PSG college is only through single window counseling by Anna University Chennai. This counselling will be based on ranking that is provided to you on the basis of marks obtained in Physics, Chemistry and Mathematics in 12th standard examination held by Tamil Nadu state board. Since the college is a reputed one, competition will be tremendous and students are expected to be in the top cutoff range to secure admissions.

Http://www.engineering.careers360.com/colleges/psg-college-of-technology-coimbatore
Visit this link you will find that this college is affiliated to Anna University. But at national level it is given that admission at this college is by JEE mains too, the national level test.
So I think admission will be according to JEE mains rank. Counseling may be done as per Anna University.