To communicate with HD13xx series or other serial-Ethernet devices, you must have HelloDevice IDE applet (or application) understand the connected device's own serial protocol or define a new one.
Read the mechanism of serial communication in HelloDevice IDE applet (or application). It will give you an insight of making your custom device communication effective. You must know the serial protocols that will be used in the device communication. With these, list up and manage serial protocols for sending to or receiving from device. After this, you must define or edit the individual serial protocols on the protocol editing panel.
Refer to this guide page for serial protocol defining and editing with rich examples.
Refer to tutorial samples page for more concrete example of defining and editing serial protocols.