The SiLabs CP210x USB to UART (Serial Port) bridge chip inside the IC-7300 needs a driver. This driver is automatically installed when on Win8.1 or Win10. No need to install the Icom supplied driver. The Audio CODEC inside the IC-7300 does not requires a separate driver install. It is so-called class-compliant. There is nothing Icom specific in the USB part of the IC-7300. Actually, when you analyze the schematics, you’ll see that the build-in interface does not differ from most external interfaces: the decoded analog audio is actually converted to digital again in the USB Audio CODEC. From a practical point of view, this is the best solution, although theoretically it might be questionable. Note that this approach, i.e. going from digital to analog to digital domain again, solves all sample rate conversion issues.
Note that the CI-V protocol is a one wire bus protocol (half duplex) and supports connecting devices in parallel. A requirement for connecting in parallel is that all devices use the same baudrate. So when USB is connected to REMOTE, the USB baudrate gets limited to the max. CI-V rate on the REMOTE port, being 19200 baud. Actually, the USB baudrate options are grayed out in the settings menu in this case.
The Icom remote software (RS-BA1) has a scope function. This function requires the baudrate set to 115200. This requires the USB to be disconnected from the REMOTE port, as explained above. This is the famous UNLINK from REMOTE setting. Unfortunately, many computer software (for example HRD free version) does not support setting a higher baudrate than 19200 for CI-V ports. So there you end up switching settings on the IC-7300 when switching software on your computer.
So could I not use CI-V via USB, set to 115200, and CI-V via the REMOTE plug, set to 19200, both at the same time? This would solve two problems: no need to switch settings and computer programs that are limited to 19200 baudrate can be used at the same time with the scope function of RS-BA1. Note that this functionality cannot be created using a software COM port splitter since such a COM port splitter requires all ports to run at the same baudrate.
I had to try this out, so I bought a USB CI-V adapter with FTDI chipset. This is actually a regular 3.3V USB to serial cable where both TXD and RXD are simply connected to the CI-V connector tip. No extra electronics required. You then have an IC-7300 with two CI-V ports, one can be set to 115200 and one to 19200 and both can be used at the same time! (the two arrows going into the CPU box in the diagram above)
This setup shows a very big plus when setting up RTTY with FSK. Often separate COM ports are required for transceiver control and FSK keying. You can now use the REMOTE port for TRX control and configure the USB COM port for FSK.
Icon uses a separate setting for digital communications on their rigs, the DATA mode. When enabling DATA mode, the compressor is disabled, input is switched and DATA mode specific filter settings are used. There is actually no need to use DATA mode for digital communications, it is just a sort of shortcut for a number of settings. That’s why DATA mode is not available on the RS-BA1 remote software, since this software already switches input when operating remote. It is important to properly “close down” RS-BA1, otherwise the modulation input setting remains on USB and your modulation is gone…
On the IC-7300, you can specify where your modulation signal (called MOD by Icom) is coming from when DATA mode is ON and when DATA mode is OFF: MIC connection, ACC connection (the 13 pin plug on the back) or USB CODEC. By default, DATA mode ON is set to ACC, this can be changed in the settings menu to USB. So, out of the box hooked up with USB, the IC-7300 does not transmit your digital mode signal. I guess that’s Icom’s way of saying that you’ll have to do a little manual reading first…