Where can i get information about the arrangement of coaches in an outstation train?

How do i know which number coach of a train is the AC coach, 1st class coach, etc? Where can i get this information before a train arrives? Sometimes, we end up running on the station to get into a specific coach. It would help if I knew beforehand the arrangement of a train.Where can i get information about the arrangement of coaches in an outstation train?it should be on the ticket number