545 or 600 is the right time zone for dep from BNC. The train should touch Coimbatore as booking from Benguluru will be under General Quota and travellers will get down at Salem Erode and Coimbatore and the seats get boarding from Coimbatore to Ernakulam/ Thrissur. Later dep after intercity at 700 will not get travelers to Kerala beyond Palakkad in normal days except peak demand season and Saturday from Bengaluru.