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RMS Serial
Communication between the RMS and the radio occurs over a serial programming cable.
- (RT-880 Only) Although the RT-880 includes a USB-C port, a standard USB-C to USB-A cable only supports battery charging and cannot be used for data communication.
A USB cable specifically designed for the RT-880 or RT-950 is required. These are available from Radtel and various online marketplaces.
Search for: RT-880 Programming Cable.
RT-950 Pro Programming Cable.
Note: The RT-950 Pro generally comes supplied with a programming cable in the box.
It is recommended to use cables with quality chipsets, such as CH340.
Avoid cheaper cables using Prolific chipsets, as they are often unreliable.
The bottom-right corner of the RMS application window contains the serial configuration controls.
These are labeled Port/Baud and consist of two drop-down selectors.
Displays all serial ports currently detected by your computer.
Select the port associated with your RT-880 programming cable.
If multiple ports are listed, an easy way to identify the correct one is:
- Open the port dropdown
- Unplug the programming cable
- Note which port disappears
- Plug the cable back in and select that port
Allows selection of the communication speed used between RMS and the radio.
Available baud rates range from:
- 38,400 up to 518,400
The maximum reliable speed depends on:
- Cable quality
- Radio tolerances
- Computer hardware and drivers
Some experimentation may be required to determine the fastest stable setting.
The configurable baud rate does not apply to firmware flashing.
Firmware flashing always uses a fixed baud rate of 115,200.
⚠ Important for macOS users
On macOS versions Tahoe 26.3 or earlier, 38,400 baud is the only working speed.
Faster speeds are working with Tahoe 26.4 or later. You may need to experiment to find the fastest reliable speed for your system.