RS232 out from Arduino Nano using micro-USB

We need to convert communication from RS232 to the mini-USB (not-micro USB) port of a Nano.
We have tried by connecting a USB to serial convertor hoping to pass the data onto a RS232-in port of our device.
The problem is that device is not seeing the data being sent out from the nano.

But if we connect the mini-USB of the nano to a laptop (USB A), we can see the data in Tera Term window.

We also tried connecting the mini-usb out -> USB-Serial convertor -> null modem cable -> Serial convertor -USB-> to the laptop.
In this case we unable to see any data in Tera term window from the nano.

Is it possible to translate(convert) the USB comunication from the Nano to RS232 electrical interface?

I would really appreciate any help on this. Thanks in advance !!!

Forget the USB socket on the board and connect a TTL serial to RS-232 adapter directly to the IO pins on the Nano. You can use pins 0 and 1 (Serial), but these pins are used for communication with your computer, including uploading sketches to the Nano. The alternative is to use the SoftwareSerial library to create a serial port on any other of the Nano's pins and connect the RS-232 adapter to those pins:
https://www.arduino.cc/en/Reference/SoftwareSerial