Solution:

Externally Powering Port Converters Some host RS-232 ports are unable to provide enough power for a “port powered” converter to work effectively. Some of those situations include: • Battery-powered handheld computing devices with low-voltage RS-232 ports • Converters connected to heavily loaded or terminated RS-485 networks • Host RS-232 ports that do not have output handshake lines connected In situations like these, B&B Electronics recommends the purchase of an externally powered converter. However, if you already have a port-powered converter, the following describes how to inject an external power source that will safely power a port powered converter. This will void the warranty on the product if damage occurs. Instructions • Only one pin in the charts listed below will require power. • Power supply ground on a DB9 is pin 5 and for DB25 is pin 7. Using formula: R = (input voltage – 6V) / (.035A) The attached diagram shows how different applied voltages are used to power the converters. The approximate resistor values current limit the circuit to 35 mA. Wire the resistor in series between the voltage source and the handshake line of the port powered converter. **Note: 9SPOP2 cannot be externally powered.