How to avoid failing a profibus communication if baud rate of 3 MBit/s and higher is chosen?
Profibus communication fails if baud rate of 3 MBit/s and higher (3, 6 and 12 MBit/s) is chosen (1,5 MBit/s and lower rates are ok).
PM 783F, CM 772F, 144 remote IOs - mostly AIs
Profibus communication speed varies based on the distance & if no proper eathing connection.
1.Larger the distance, lesser the speed you can achieve.
2.Don't change the speed on fly it will cause on & off of all slaves.
Note that <=1.5MBPS is tested when all the 32 slaves are connected in a segment with 1m difference.
Please don't change the Communication settings(1.5MBPS) let it be default.
please note that configuration changed (baudrate etc) needs plausibility check and download to the controller. as well all connected slave types requires hardware reset to change their baudrate.
Also which I/O's and slave you are using with, is it S7/8/900 ?
As replied in above answer if your profibus setup meets all the requirement for 3-12 MBit/s baudrate. i.e distance is under range. based on IO count if it's S800 IO then I guess you must be having 2 or 3 profibus slaves in probus netwrok so that is not an issue. but which slave you are using ? Incase you are using CI840 and there is RLM(Y-link) inbetween master and slave then note that you need to change baudrate on RLM according to baudrate changed in CM 772F.
Hope this helps...