At 2004-02-10 08:04, rhonn tabanao wrote: >"> - Buy a little box with two RS-232 connectors >> (generally 25 pins, >> but perhaps there are also 9-pins versions now) >> with 9 two-color >> LED's that indicate the state of the 9 most >> important lines." > >Sound interesting.. >Is there a schematic for this device?? >Thanks again.
I don't know about a schematic, but this is an example of what I am talking about: http://www.lindy.com/de/productfolder/04/43014/index.php And here is another: http://www.bb-elec.com/product.asp?sku=232MTT&dept_id=136 And here is a 9-pin version: http://www.bb-elec.com/product.asp?sku=9PMTT On page: http://www.airborn.com.au/rs232.html there is an explanation: > >Using a Breakout box or LED box to work out cabling > > > >If you have problem with RS232 cabling, your best "emergency" tool may be a breakout >box (sometimes called an LED box). Generally these units only come in the DB25 size, >but with a couple of DB9 to DB25 adaptors, they can be used with DB9 cables as well. >The units have an LED for each signal line in the cable, and the LED lights green or >red dependent on the signal state. The Breakout box also allows you to disconnect >certain lines in the cable, and patch in new ones - good for trying new cable wiring >possibilities. > >The first thing to remember, is that there is a good chance the two devices you are >trying together will actually work if you can get the cable correct. If you have some >other way to actually prove this - for instance by trying each of the devices on >another system - do it. > >Given a hypothetical example - for instance connecting a standard PC with a DB25M to >a 200 disk CD changer with a DB25M, the first thing I would try and do is get a cable >that I think would work. In this instance, I would either purchase or build a >null-modem cable (DB25F to DB25F) - similar to the last example, basically the cable >used to connect two PCs together with handshaking, only DB25F to DB25F instead of >DB9F to DB9F. > >Given the cable that I believe will work, connect the cable, LED box and two devices >all together. Before powering on both devices, unplug just one of them. Power the >devices on and make a note of which LEDs are lit. Then unplug the connected device >and plug in the disconnected one, without rearranging the cabling otherwise. Again >make a note of which LEDs are lit. If any single LED is lit by both of the devices, >then there is an output conflict, and the cable wiring is incorrect. By this, I mean >that one line in the cable has an output driving it from both ends - and this is not >correct for RS232 - so that means that the cable wiring is not correct for the >devices. Pay particular attention to Tx and Rx. > >To continue with the example above, if I saw that two ends were driving the same >lines, I would assume the null modem cable was not correct, and I would try a >one-for-one gender changer instead. > >If each end drives its own set of LEDs, connect the two ends together. In normal >situations, you should see all the LEDs light up - but there are some devices which >will not light up all the LEDs. Having said that, if one of the devices is a PC and >any LED except RI (Ring indicator) is not lit up, the cable will probably not work. > >Normally, other cabling problems will involve handshake lines. An LED box will be an >invaluable guide, but there is no trivial test to determine the solution. An LED Box >will also show the lines as they change state, although it is usually quite hard to >see the serial communications themselves unless the comms are continuous, or at a low >baud rate (9600 baud or lower is usually visible). They are a bit more expensive then I remembered: 15 euro or more, but you only need one and they will last for a lifetime. I used 'RS-232 led' as a search term in Google to find these pages. Greetings, Jaap -- Author: Jaap van Ganswijk INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
