May 8, 2026 · Guide

Serial Terminal for macOS: Alternatives to screen, minicom, and CoolTerm

By Dzulfikar Ats Tsauri, founder of Voltrus / JoyoDigitama. He builds the protocol tools covered in these posts. Updated October 28, 2026.

If you work with industrial hardware, embedded systems, or network infrastructure on a Mac, you need a serial terminal. It is the tool you reach for when you are configuring a Cisco switch over console cable, debugging a Modbus RTU device on RS485, flashing firmware to a microcontroller, or reading data from a PLC through a USB-to-serial adapter. For background on the underlying communication standards, see our guide to serial communication protocols.

The problem: the built-in serial tools on macOS are barebones, and Apple Silicon has added a layer of driver headaches that many serial apps leave to the user.

This guide surveys what is available in 2026, what to actually look for, and which tools are worth your time.

The State of Serial Terminals on macOS

macOS has never shipped with a purpose-built serial terminal application. What you get instead is a collection of CLI tools and third-party apps of varying quality. Here is the landscape:

screen /dev/tty.usb*

macOS includes screen as a built-in terminal multiplexer that can connect to serial ports. It works. It is also the most common source of frustration for engineers new to serial communication on macOS.

• No hex view. You see ASCII only. Binary data, Modbus frames, and raw sensor output are unreadable.
• Confusing exit sequence. To disconnect, you press Ctrl+A then Ctrl+\ (or Ctrl+A then k). Most people just close the terminal window and hope the port is released properly.
• No baud rate UI. You specify everything on the command line: screen /dev/cu.usbserial-1410 115200. Get one parameter wrong and you get garbage.
• Limited logging. screen can write the session to a file (-L, or Ctrl+A then H), but the log is plain text with no hex view and no per-frame timestamps.

For a quick check on a console port, screen is fine. For anything beyond that, it is inadequate. A note on device names: macOS creates both a /dev/tty.* and a /dev/cu.* node for each serial adapter. The tty.* node is the dial-in device and can block while waiting for a carrier-detect signal, so use the cu.* (call-out) node when you open a port yourself.

minicom

Installable via Homebrew, minicom provides a terminal-based UI with configuration menus accessed through Ctrl+A then Z. It is a port of the classic Linux tool and feels like it. The keyboard-driven interface was designed for a different era.

• Supports baud rate configuration, parity, and stop bits through a menu.
• Can capture session output to a file.
• Has a display-in-hex option (-H), but no protocol awareness.

picocom

A minimal serial terminal available through Homebrew. It connects to a serial port with a specified baud rate and has no configuration menus. It does support logging to a file (--logfile) and sending hex bytes by hand, so it is more capable than it looks, but there is no hex traffic view or frame decoding for hardware debugging work.

CoolTerm

A free, cross-platform serial terminal with a graphical interface. Developed by Roger Meier, CoolTerm is popular in the maker and education communities because it just works. You select a port, set the baud rate, and connect.

• GUI with port selection and configuration options.
• Supports hex display in a basic form.
• Can log data to a file.
• No protocol analysis. You see bytes, not structured frames.
• Interface feels dated and was not designed for professional debugging workflows.

Serial by Decisive Tactics

At $39.99 (price on the Decisive Tactics site, checked October 2026), Serial is the most prominent paid serial terminal on macOS. It has a clean interface, handles port detection well, includes built-in support for common USB-serial chips, runs natively on Apple and Intel processors, and includes a hex view, timestamps and logging. Where it stops for industrial work:

• Built around terminal emulation. Its strengths are xterm/VT100 emulation, break sequences and file transfer for routers and switches.
• No Modbus frame decoding listed. If you need Modbus RTU frames annotated with slave address, function code and CRC status, you decode them by hand.

What Happened to USB-Serial on Apple Silicon

The transition to Apple Silicon complicated serial communication for some engineers. Here is why:

Kernel extensions are deprecated. Apple introduced system extensions and DriverKit in macOS Catalina (10.15) as the replacement for kernel extensions. Since macOS 11, third-party kexts can no longer be loaded on demand and are merged into an auxiliary kernel collection at boot, and on Apple Silicon loading a third-party kext also requires lowering the startup security policy. Older USB-serial drivers from chip vendors were built as kexts.

The practical result: how well a given chip works depends on the chip, the driver version and the macOS release.

• Check the vendor's current macOS driver. FTDI, Silicon Labs (CP210x), WCH (CH340/CH341) and Prolific (PL2303) each publish their own macOS driver downloads; confirm that the one you install matches your macOS version.
• Counterfeit chips. Cheap adapters sometimes carry counterfeit FTDI or Prolific chips, and vendor drivers have been reported to refuse some of them.

DriverKit is the way forward. DriverKit drivers run outside the kernel, so a bug in the driver cannot panic the Mac the way a kext bug can.

What to Look for in a Serial Terminal

If you are doing professional hardware debugging, industrial automation commissioning, or embedded systems development, these features matter:

• Hex view. Binary protocols do not make sense in pure ASCII. You need to see the raw bytes. This is non-negotiable for Modbus RTU, custom binary protocols, and any device that sends non-printable data.
• Configurable serial parameters. Baud rate (including non-standard rates), data bits, parity and stop bits. Every device has different requirements.
• Timestamps. When you are debugging an intermittent communication failure, you need a timestamp on every frame sent and received. Millisecond precision matters when analyzing timing-sensitive protocols.
• No kernel extensions. On Apple Silicon, the app itself should install no kext and work with whatever serial port the adapter's driver creates.

Comparison: Serial Terminal Apps for macOS

MacTools Serial Terminal: Feature Deep Dive

MacTools Serial Terminal was built for engineers who need more than screen provides: a readable view of binary traffic, exact-byte sending, and a way to test without hardware.

Hex Traffic View

Every received and sent frame lands in a live table as hex bytes, tagged RX or TX. This is essential when working with Modbus RTU frames, binary sensor data, or any protocol that mixes control characters with readable text.

Millisecond Timestamps

Each frame is stamped to the millisecond, so you can see inter-frame gaps, slow responders and retries directly in the traffic table.

Hex or ASCII Send

Type a command as text, or paste raw hex such as 11 03 00 6B 00 03 76 87 and send exactly those bytes.

Virtual Serial Port

On macOS the app can create a PTY-based virtual port. Point another program at its /dev path to test serial code with no adapter attached.

USB-Serial Adapters

MacTools installs no kernel extension of its own. It opens the serial ports macOS exposes, so it works with adapters built on the common USB-serial chipsets:

• FTDI FT232 (FT232R, FT232H, FT2232)
• WCH CH340 / CH341
• Silicon Labs CP2102 / CP2104 / CP2105
• Prolific PL2303 (including handling of counterfeit chips)

If your adapter shows up as a /dev/cu.* device, MacTools lists it. If it does not, install the chip vendor's current macOS driver first.

RS485 and Modbus RTU Debugging

RS485 is the physical layer for the majority of Modbus RTU deployments. If you are commissioning a solar plant, a building management system, or a factory automation line, you are probably talking Modbus RTU over RS485. Debugging this requires seeing the actual bytes on the wire. For understanding the differences between RTU and TCP variants, see our guide comparing Modbus RTU vs TCP.

Here is how a hex-capable serial terminal changes the debugging workflow:

Seeing the Raw Frames

When a Modbus RTU device is not responding correctly, the first question is always: what is actually on the wire? Without a hex view, you are guessing. With MacTools Serial Terminal, you see every byte of the request and response with its timestamp.

A textbook example of a Modbus RTU read holding registers request (3 registers starting at address 107 from slave 17), not a capture from a device, looks like this in raw hex:

11 03 00 6B 00 03 76 87

Reading it byte by byte:

• Slave Address: 0x11 (17)
• Function Code: 0x03 (Read Holding Registers)
• Start Address: 0x006B (107)
• Quantity: 0x0003 (3 registers)
• CRC: 76 87 (low byte first; valid)

CRC Checking

Modbus RTU uses CRC-16 for error detection. On a noisy RS485 bus, corrupted frames are common. Copy the frame from the hex view into a CRC-16/Modbus calculator to confirm whether the last two bytes match; a mismatch points at wiring, termination or noise rather than the device's configuration.

Timing Analysis

Modbus RTU has specific timing requirements: a silent interval of at least 3.5 character times between frames. With millisecond timestamps on every frame, you can check that your master is sending requests with adequate spacing, and that slave devices are responding within the expected timeout window. This is invaluable when debugging devices that randomly drop off the bus under load. For a broader look at how Modbus compares to other industrial protocols, see our industrial protocol comparison guide.

Further Reading

• OPC UA vs Modbus TCP: Which Industrial Protocol to Choose
• Best Modbus Simulator for macOS (2026): PM5560, SMA Inverter, and More
• Modbus Poll Tool for macOS: Read, Write and Monitor Modbus TCP/RTU Devices