On Jan 13, 2011, at 2:18 AM, Farzin Kamangar wrote: > Dear EMC users, > I am using the cable shield and the input pins of the parallel > ports to > make any input on or off. When the shield is not connected to the > input pin > it is on or in 1 state and when it is connected to the pin it makes > the pin > off or have zero level. Now my concern is that how can we isolate > the input > pins from external signals (e.g. use an optocoupler or a relay)? > This way I can eliminate the chance of connecting an abnormal signal > voltage > to the input pin of the parallel port. For instance connecting 24 > volts to > an input pin instead of the > parallel port cable shield (zero signal) by mistake. Thanks > Farzin
farzin, like you mentioned already, using a opto-coupler is usually the way to go, given that your incoming signal can drive the opto-coupler device. Else you need to make a little circout to boost that signal. Ries ------------------------------------------------------------------------------ Protect Your Site and Customers from Malware Attacks Learn about various malware tactics and how to avoid them. Understand malware threats, the impact they can have on your business, and how you can protect your company and customers by using code signing. http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
