What is the maximum cable length
for RS-232 powered devices?
Not exceeding 15 meters at a speed of 9600bps
Devices powered by the computer’s RS-232 port are powered by the Tx, RTS, and DTR lines. In general, the cable length should not exceed 15 meters at a speed of 9600bps. If you use a longer cable length, the transmitted power may not be enough to power the device.