In general, the distance depends on connection type. If profibus connectors connected to LULC07 are equipped by inductors (to avoid reflections) then there is no min cable length. Connectors with inductors are mandatory for bus speed above 1.5M. When using the connectors without inductors, there must be min cable distance between 2 neighbor nodes. Profibus general guide recommends min 1m, but for LULC07 , also due to 4-wire profibus cable, declared min cable distance is 0.3m. Consider max 1.5M baud rate for connection without inductors.
Recommended connector (with built in inductors) is LU9AD7
Recommended connector (with built in inductors) is LU9AD7