RS232 Hardware issue

Projects General Guidance
1

Hi Folks,

i am currently trying to get my Arduino Uno to communicate to either a digital VT320 or VT220 terminal that were going to be scrapped off at work.

Now I have had the terminals communicating with my laptop Via a RS232 to USB adaptor with no problems. As a starting point I have also uploaded the "SerialCallResponse" sketch to my Arduino Uno which appears to be working via the standard USB and the Serial Monitor built into the Arduino Software.

However When i connect my fleabay RS232 shield, so that i can connect my VT220/320 terminal to the arduino, I get nothing. Both are set at a baud of 9600 but even so i get nothing.

I am not sure whether it it just my cheap RS232 shield or if its something else. for reference, here is a link to the Shield I bought. http://www.ebay.co.uk/itm/261119405859?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Any ideas?

2

Are the RX and TX lines connected correctly? Both devices might be set as DTE.

3

well the Schematic of the Shield shows it uses the MAX232.

It has T1Out (14) going to Pin 2 of the 9 way D-type and R1In (13) going to Pin 3 of the 9 way D-type

Am I right in saying that according to this page:

R1In (13) of the MAX232 should be connected to Pin 2?

and T1Out (14) of the MAX232 should be connected to Pin 3?

4

All fixed!

As you said, the TX and RX lines where the wrong way round for DTE to DTE comms. So i have just soldered some fly leads in place and it works!!!

:smiley: