 485SD9R 485SD9TB 485DRJ 485SD9RJ 485LPCOR 485BAT3 4WSD9R 4WSD9TB Port Powered RS-232 to RS-485 Converters - Papyrus Computer Technologies Ltd.
Those devices allow conversion of RS-232 to RS-485 with no power supply. These port-powered converters change TD and RD RS-232 lines to RS-485 signals. All are port powered and feature Automatic Send Data Control. SDC automatically enables the RS-485 driver when data is present on the RS-232 side. Control of the driver is automatic at rates up to 115.2 kbps.
Powered from RS-232 handshake lines, no power supply needed!
Automatic Send Data Control - no software drivers needed!
Certain devices allow use of alternate power supply methods.