problems with rs232 to ttl converter

I’m completely new to Arduino.
I want to realize a NMEA repeater using my old Garmin 45XL GPS, Arduino and a serial LCD display. I have a RS232 to ttl converter (based on the MAX3238E) to let GPS to talk with ARDUINO board serial input but I’m not able to use it.
I connect the DB9 connector of Garmin data cable to the converter, 5V and GND from ARDUINO board to 5V and GND of converter, but there is no output from converter.
Where I’m wrong ?
Is there any way to test the converter ?

Thank you for any help.

You might want to double check on the RS-232 side that you have an output signal going to a input pin of the convertor, it’s easy to get send and rec mixed up because it’s an ambigious name as both sides send and rec. Same applies to the TTL side, output pins wire to input pins.

Also if you want you can check out your convertor if you have access to a PC with a true com port by plugging that into the RS-232 side of the convertor and then wire a temporay jumper between the TTL send and rec pins. Then run a communications program on the PC and see if typed characters get echoed back to the PC.


Thank you Lefty! I triple checked everything, I tried to swap RX and TX several times, and finally … it works!
Thank you very much !

Your welcome, but you did the work :wink: