How many PROFIBUS DP repeaters can be placed in series?
In some documentation you will see a maximum of 3 repeaters, even in the standard a reference value of 3 is written, but this is NOT completely true. The internal electronic components of the repeater will determine the maximum number. The data regeneration in the repeater will make bits smaller or wider. If you put too many repeaters in series, messages are not recognized anymore, because the bits differentiate too much. Repeaters with no limit are also available. So, check the manual of the repeater! It should state the maximum amount. For example: the Siemens repeater is 9, the ProfiHub is unlimited. The second step is changing the busparameters. All repeaters have a delay time. If you put a lot of repeaters in series you have to change the Tslot busparameter in the DP master to a higher value. In the manual of the repeater it should state what the value should be.
