There is no power requirement in the RS232 specification.
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I have a power requirement from the Serial port!! Trying to run a POS Metrologic Scanner from my PC. We've thrown all the transformers out as we don't use them lol...except now! But rather than buy one I thought it may be possible to fiddle the motherboard to allow power through the Serial port. That's what we do with our till bases...
POS machines tend to use proprietry ports or have the ability to inject power as a feature specific to their use as a POS terminal to run certain devices. If you're trying to use a barcode scanner on a regular PC then you'll most likely need a separate DC supply for it.
Depending on the input voltage required you might be able to get a connector to draw power from either USB or PS/2, but I don't know the specific requirements of the device so couldn't say for certain.
I have a power requirement from the Serial port!! Trying to run a POS Metrologic Scanner from my PC. We've thrown all the transformers out as we don't use them lol...except now! But rather than buy one I thought it may be possible to fiddle the motherboard to allow power through the Serial port. That's what we do with our till bases...
What I mean is the RS232 specification makes no provision or requirement for power at the serial port on a normal PC.
As BigDave says proprietary solutions may do but they do not fit the specification of a serial port on a regular PC/RS232 device.
I currently run an old scanner (we're phasing in new ones), with its own power supply.
So before ordering in a power supply for the new ones, thought it maybe possible to get power from my serial port - have done alot of searching around myself and nope, not possible.