Impact - The break out boards I have been looking at buying use opto-Isolation to prevent any current from going back to the PC through the port. I think this is one of the main advantages to using a seperate breakout board in addition to what Ger21 said about allowing you to use another parallel port to add on many more features and it keeps all those functions seperate from your controller port. Same goes for the relays I have been browsing they all are opto-isolated to prevent current going back to the breakout board/pc. At least thats my take on how things work from the searching I have been doing into breakout boards and relays for my xylotex.
Good Luck
Bowman |