Recently I purchased this SIM5300E shield and have been having trouble interfacing with it. I connect the debug USB port to my computer and connect to the com port via PuTTY. The responses to AT requests can be seen in the image.
Responses on COM Port to AT commands:
This is not due to baud rate as I have tried many different ones and I always get the "SIO:" message after the AT command. I have also tried other COM ports but they do not output anything