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Topic: TTL RS232 problems (Read 1 time) previous topic - next topic


I have a sketch I have uploaded to my duemilanove that outputs rs232 commands to control and extron matrix switcher. I have connect up pins 0 & 1 to a ttl-rs232 shifter to make sure I am sending rs232 levels. When I connect the rs232 connection to my other computer using a keyspan rs232 to usb adapter I get the ascii command I need but when I connect it to the Extron switcher I get nothing. I have checked the serial commands, the cables and connections and all seems fine, it just doesn't seem to want to work.

I was wondering if because I have connected VCC of the shifter to 5v from the duemilanove that this might not be able to drive enough voltage to achieve correct rs232 levels, is this possible/likely or have I missed something else.
Cheers for any advice you can offer.


or have I missed something else.

Look up DTE and DCE, you will see that depending on the type of device the TX can be an input or output with the RX vice versa .
That might be your problem here.


You may also have to do something about "handshake".

A suggestion: It may (or may not!) help to first do some experimenting with driving your serial device from a PC. If you use Windows, Hyperterminal or PuTTY would be suitable software. This might give you "first success" with making the device Do Things, and when you've solved the problems of driving it from the PC, you could then go on, armed with some knowledge you didn't have before, to driving it from the Arduino.

There are some general notes about talking to serial things via Arduino at...



Thanks for all the advice, I have tried reversing the TX and RX and had no success unfortunately. I have already connect the switcher to the PC and have the full list commands and settings working on the switcher, it just doesn't seem to be registering.
I will try it with another matrix switcher and see if that is the same.
Thanks for all the advice.


Did you ever have any luck controlling the Extron piece with your Arduino?  I am attempting to control an Integra AV Receiver with an Arduino and am looking for someone who has successfully controlled some AV gear. Hope things are well with you!

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