Arduino UNO: Send & Receive via DB9 - RS232

Hello,

I am needing help regarding the Arduino UNO. I am trying to send functions to a controller and then receive the data back from the controller to my Arduino UNO. The problem is my controller has an DB9 RS232 connection that uses (TX, RX, CTS, & RTS). So how exactly should I connect the Arduino UNO to my controller. My ultimate goal is to automate my controller by using the Arduino UNO. The Arduino UNO will automatically send functions (i.e The functions are: 1#, 2#, 3#, 4#, 5#, 6#, 7#, 8#, 9#) to my controller and my controller will automatically send back to the Arduino UNO with its responding data to that function (i.e. By sending 1# to the controller, the controller should respond back with it's voltage). Im very new to coding in Ardunio language. I originally wrote my code in C# and it worked fine but now I have to use an Arduino which isnt compatible with C#. Also, are there any additional code that I may need to add since I am trying to connect a DB9 RS232 to my Arduino UNO?

Thanks

You need something like a MAX232 to convert the Arduino TTL levels to RS232 levels. You might be able to ignore or short RTS/CTS. Else you need to convert those signals as well to RS232; I haven't used RTS/CTS for ages so you have to do some research yourself (if you don't know already) what they do and implement that in the Arduino.

Are you planning to use SoftwareSerial or the HardwareSerial? For the latter, be aware that the USB chip also uses that and that you might need to disconnect at least the RX line while uploading.

Didn't I answer this elsewhere for you with links to adapter cards?

CrossRoads:
Didn't I answer this elsewhere for you with links to adapter cards?

Oh?? In that case this might be a pure coding question.

Yes, here it is:
https://forum.arduino.cc/index.php?topic=390447.msg2689702#msg2689702
This topic locked.

Don't crosspost - one question, one topic, have a little patience for an answer.