One such program is: 'Serial 2' by Decisive Tactics. Get a serial communications program that directly supports the Prolific Dongle.If you have a Prolific Dongle then you have a number of options: So if using Prolific Dongle just make sure you have updated to lastest MacOS version. NOTE #2: Retesting with Big Sur 11.2.3 the Prolific Dongle now works with built in Apple USB driver. NOTE: The exact device name may vary from one machine to another. If you have a FTDI based USB dongle then you can start a serial communications session using the in-built 'screen' application via a Terminal window: 'screen '.Īs a example, for serial communications session at 38400 Baud (on my machines, Terminal window): 'screen /dev/tty.usbserial-A50285BI 38400'. Retesting with Big Sur 11.2.3 the Prolific Dongle reports as: '/dev/tty.usbserial-1430' Using FTDI Dongle In MacOS Catalina and earlier the Prolific based devices where available as: '/dev/tty.UC-232AC'. On my Mac the device is: '/dev/tty.usbserial-A50285BI' About This Mac - Systems Information Report (ATEN/Prolific Dongle) If you have a FTDI device then you should be able to find the RS-232 devices by opening the Terminal and doing: 'ls /dev/b*' To see what type of Dongle you have look at the 'About This Mac' report under USB: About This Mac - System Information Report (FTDI Dongle) It reports as: '/dev/tty.usbserial-1430' on my Intel MacBook Pro.

NOTE #1 - As per feedback (below) from 'Brandon Applegate' and 'David Rankin' below I retested my Prolific PL2303 with Big Sur 11.2.3 and am happy to report that the Prolific PL2303 Dongle now works again. Currently there is no Big Sur device driver available for the Prolific based USB Dongles.

MacOS Big Sur has FTDI based devices supported by in-built Apple device driver. The USB dongle requires a device driver, which with MacOS Big Sur need to be 'notorised' (signed) to work.

FTDI Chips - 'Future Technology Devices International' based dongles use community developed drivers.

Prolific PL2303 Chips - used by ATEN USB/RS-232 dongle.

These are sold under various brands but most are based on either: To allow newer USB equiped computers to talk to RS-232 based devices you need a USB to RS-232 dongle. Nowaday's pretty much every desktop, notebook and server computer have USB ports and RS-232 ports are only on either specialist or older devices. USB 1.0 was introduced in 1995 and is now in its forth generation with USB4, which means USB is now over 25 years old. So for those of you who still have the need for RS-232 Communications and use Apple Macintosh computers here is the Big Sur low down. The latest 'thing' to break with MacOS are some USB to RS-232 Serial Communications dongle drivers. Status: Updated May 2021 - Big Sur 11.2.3 - Tested with ATEN (Prolific PL2303) and FTDI RS232R USB Dongles

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