Data Rate / Line Length chart from RS-422 Annex A (This chart is not in RS-485) This chart is not an absolute limit, but a conservative guide based on empirical data of 24AWG telephone cable. Cable length may be extended from this chart. Chart created with Excel from following data: Cable Length in Meters Data Signaling Rate in kBits/Sec 10000 1200 90000 1200 10000000 14 .