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Is there a known problem using a 2 pair x 0.75mm2 (24/0.2mm) armoured screened cable (27.2 ohm/km, 88 pF/m) for RS485/Modbus comm, approx distance of 100 metres - will it be advisable just to use a twisted pair, e.g. from Belden to avoid any problems (noise, etc)? The signal is from/to a variable speed drive - DCS. Should the capacitance of the cable has to be lower than 88 pF/m to have a good signal for Modbus RTU?