What is the max cable length for an RS232 part? Is a 5m cable ok for the ADM101E?
A general rule of thumb for RS232 is 50ft/15m max cable length. The exact figure depends on the capacitance of the cable and the data rate. The lower the capacitance and the lower the data rate, the longer the cable can be.
The ADM101E is specced at 460kbps max data rate at Rload = 3kOhm and Cload = 1nF. A typical cable will be 47pF/metre. Therefore the max cable length is 1nF/47pF = 21metres.
Or if you assume a 5m cable length, then the capacitance of the cable needs to be < 200pF/metre to ensure spec conditions are met at max data rate.