UPXtreme with RS232 isolator.

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Hi,
I'm using UPXtreme in one of my projects in which I want to communicate via its serial port COM1 with an RS232 communication protocol to a slave RS232 device and I want both devices to be isolated from each other to avoid ground loops.
The communication works properly when the device is directly connected to COM1 unisolated, but it doesn't work if I introduce the RS232 isolator.
The isolator which I'm using is:-
https://iotmart.advantech.com/Serial-USB-Communications/Serial-Converters-Repeaters-Surge-Protectors-Isolators-and-Repeaters/model-BB-9SPOP2.htm

I'm using the UPXtreme on DTE side and slave on DCE side.
Any help will be appreciated.
Thanks,
Vinay