2 Jun
2009
2 Jun
'09
8:39 a.m.
On Tue, June 2, 2009 4:45 am, Johnny Billquist wrote:
He's not talking about powering the device, he's talking about driving
the signal lines. Their input impedance isn't infinite, you know!
-Dave
--
Dave McGuire
Port Charlotte, FL
USB only
guarantees to supply 100 milliamps. Up to 500 mA can be
negotiated with the controller, depending. Might your older device
depend on more amps than the USB adapter can supply?
Huh? The RS-232-port isn't supposed to deliver any power at all. Some
devices admittedly abused the RS-232 by using something like DTR to
actually supply the power needed to drive the thing, but that is abuse.
But I'd be surprised if a circa-70s modem was ever designed to use the
power from the RS-232 port to drive the modem itself. I'd expect it to
have an external power supply.