Newsgroups: sci.electronics.misc Subject: Re: Easiest LED indication of rs232 activity? References: <1069763743.271658@gurney> "Frode Undseth"writes: > Hi all! > > I'm trying to figure out the simplest way of getting a visual indication > of activity on a rs232 Tx line. I know rs232 is using +-12V for signalling, > but is it possible to drive a led through a resistor directly between the > signal line and 0V withouth weakening the rs232 signal too much? Yes with suitably high resistance value and sensitive LED you can get useful visual indication. > Has anyone tried this, There are many commercial RS-232 gadgets built in this way around. Many small boxes that you connect between two RS-232 connectors and have LEDs to so RS-232 signals just have a set of bicolor LEDs and suitable resistors for current limiting inside them. I don't have resistance values in hand, but I quess that the serial resistors used in those have value of few kilo-ohms. > or are there other better, cheap and simple methods I could use? Nothign comes to my mind that would be simpler and cheaper. > Any idea is appreciated.. > > Thanx for any help! > > Kind regards, > Frode Undseth > > -- Tomi Engdahl (http://www.iki.fi/then/) Take a look at my electronics web links and documents at http://www.epanorama.net/