These release notes apply to every platform build. Download details stay in the platform picker.
Features
A restricted device is told why, instead of quietly running on: The server can now restrict a machine by device (for instance after a license activated on it was refunded). On the next launch report, the application closes its ports, shows a "Device restricted" dialog with the server's explanation, a contact address and a link to the Terms of Service, and exits when it is dismissed. The verdict is cached on the machine: the next launch asks the server once more (up to 5 seconds) and shows the main window only on an explicit "not restricted"; a refusal or an unreachable server ends in the same dialog, with a hint to connect to the internet and start again if the restriction has been lifted. A machine that was never restricted is untouched, and an unreachable server still lets it through. The App Store build takes no part in this
Interface
The registration prompt now explains where Free ends and Pro begins: The direct build's "30-day free trial" window still spoke shareware — "after the trial period you must register the program or remove it from your computer" — which is no longer how the product works: Free stays available when the trial ends. The window is now titled "Free and SPU Pro" and says that direct downloads include a 30-day Pro trial from first launch with Free available afterwards; that Free supports one connection and local logs while Pro unlocks multiple connections, bridges, the Modbus request builder, file transfer and settings sync, with saved project files and logs kept either way; that a Personal license bound to an Alithon account activates the signed-in computers and Enterprise activation follows the seat count; and that Live Sync is available in Free within its cloud traffic limits. The buttons read "Buy SPU Pro" and "Continue trial" or "Continue with Free", whichever applies. The App Store build's subscription note likewise opens by saying that Free basic debugging needs no subscription. The Windows installer's license text says the same
Fixes
A colleague signing in was refused an enterprise key once the buyer had bound it: A bound key answered to its owner's sign-in alone, whatever its edition — but an enterprise key is bought as a number of seats for machines that several people sign in to, and the buyer is rarely the one at the keyboard. Once they ticked the binding, a colleague typing the same key got "This license key is bound to a different account", and signing in with their own account at startup wiped the machine's enterprise activation. An enterprise binding now only says who manages the key: it appears in that account's dashboard, seats can be released from there, and colleagues keep activating seats with their own accounts and keep them on sign-out. Only a personal key is its owner's alone. The binding hint in the license window says so for enterprise keys
A refunded or disabled license stayed Pro on the machine it was activated on: Once the server disabled a key (refund, administrator action), every launch merely added a "DISABLED LICENSE" warning box; the machine's own license data was left untouched and Pro kept working until the expiry date. A disabled reply now clears the local license the way a sign-out release does, switches to the free edition and warns once; the application keeps running
Version archive
Previous releases
Choose a platform to review older builds and their release notes.
App Store 版收留官网买的授权码: 在官网购买过永久授权的用户装上 App Store 版后，授权本身是被认可的，却没有任何界面能把授权码输进去——换一台新 Mac 就彻底断了路，只能改装直装版。现在订阅窗口里多了「输入授权码」入口，打开的就是直装版那个授权管理窗口（按 App Store 规则不含购买入口）；绑定到 Alithon 账户的授权码更简单——登录即激活、退出登录即释放，与直装版一致；已装有授权码的副本启动时也会像直装版一样向服务器核对续期与禁用状态
The App Store build now takes a license key bought on the website: A perpetual license kept unlocking Pro in the App Store build, but there was nowhere to type its key in — a new Mac was a dead end short of switching to the direct download. The subscription dialog now has an Enter License Key entry that opens the same license window as the direct build (minus the buy button, per App Store rules); a key bound to an Alithon account still activates on sign-in and releases on sign-out; and an installed key is checked with the license server at startup for renewals and disabling, exactly as in the direct build
Parameter changes reach an open port at once: Editing the baud rate, framing or flow control in the quick settings did nothing to an open serial port — the value was stored for the next open, the status bar kept showing what the port actually ran, and nothing on screen said so. It was the only parameter path in the application that did not take effect immediately (switching ports reopens, an RFC 2217 client pushes SET-BAUDRATE, Live Console reopened). The change now lands on the open port in place, without a close-and-reopen — a reopen drops DTR and resets most dev boards, which is not what "set the baud rate" asked for. A value the driver refuses rolls the accepted ones back too, so the port never runs a mixture; a transfer in progress refuses the change and says why. Live Console and the headless CLI take the same path: on failure the port stays open with its previous parameters instead of disconnecting
Interface
Stop bits join the quick-settings drawer: The connection group's default-hidden fields used to be Data Bits and Parity only; Stop Bits (nearly always 1) now stays off the panel out of the box too, still editable in the settings dialog. Anyone who has configured that group's visible fields is untouched
The Microsoft Store build puts an icon on the desktop: The Store install used to reach no further than the Start menu. Installing now creates a desktop shortcut (on Windows 10 build 19645 and later; older systems install as before, just without it)
Fixes
The Help menu offered the subscription twice in the App Store build: "Subscribe to SPU Pro…" and "SPU Pro Subscription…" opened the same dialog, and read identically while unsubscribed. One entry remains, its label following the subscription state
The App Store build called a legacy license a subscription: A perpetual-license holder was told twice over that they had subscribed: the registration button read "Subscribed" and the Help menu "SPU Pro Subscription…" — a subscription they never took out. Both now follow where the entitlement actually comes from — "Licensed" and "SPU Pro License…" — the way the About box already says "SPU Pro (Legacy License)"
Leaving serial for a network target never stopped the old session: Switching an open serial port to a network target (Live Relay, RFC 2217, TCP/UDP) in the inline editor closed only the port handle; the session state stayed "running", so the toolbar kept Start greyed and Stop armed while nothing had dialled the new target, and only a manual Stop/Start cleared it. The settings dialog had the same hole one layer down: a mode change adopted the new model without ending the old session, leaking the old transport where Stop could no longer reach it. Both paths now stop the old session first
A long PAUSE ate memory, and resuming froze the window: PAUSE diverted every incoming byte into an unbounded buffer — an afternoon of pause on a busy link was an unbounded allocation — and resuming replayed the whole backlog as one giant frame, one decode and one insertion that froze the window for seconds. The pause buffer is now capped at the display buffer size, dropping the oldest bytes so what you un-pause to is the newest; the Rx counter counts at arrival, so the wire statistics never shrink to what survived the cap; and the resume replays in 64 KB frames under a 256 KB-per-tick rendering budget, keeping the window responsive throughout
An open find bar pinned the interface under streaming traffic: With the find bar open, every 20 ms display tick that carried data re-scanned the entire receive document — find, filter and highlight each time — and a large document under continuous traffic pinned the GUI. Traffic-driven rescans now coalesce to at most one per 250 ms; typing a keyword, F3, the option boxes, a send echo, stop and clear still refresh at once
The license key no longer reaches the log: Checking a license used to print the raw key, its hashes and the signature to standard error along with the rest of the debug output — on macOS, that is the system log. Debug output is now off by default and grouped by module, to be switched on only when something needs looking into; the license lines are gone for good. Start-up also loses the warning about a missing font family, and the 70–80 ms font-alias scan behind it
Download
| Platform | File |
| --- | --- |
| Windows 10 1809 or later, 64-bit | serial_port_utility_*.exe |
| macOS 12 or later, Apple Silicon | SerialPortUtility-*.dmg |
| Linux x86_64 (Ubuntu 22.04 or later) | serial-port-utility-*-linux-x86_64.tar.gz |
First-launch notes for each platform — Gatekeeper on macOS, the runtime libraries on Linux —
are in the README.
状态栏弹出菜单会把状态提示留在栏里: 点开 Live Sync 格子、指针从"实时终端"移到弹出菜单自己的条目上，Qt 把清除提示发给了弹窗——它是一个独立的窗口，主窗口收不到，那句提示就在状态栏里留一整场，端口状态与流量计数一直被它盖住。现在这类提示统一转发到主窗口的状态栏
English
Features
Licenses can belong to an account, so signing in activates the machine: A license key and an Alithon account used to know nothing about each other -- the key knew machine ids, the account knew devices and orders -- so every new machine meant finding the delivery email again. Tick Bind the license to my Alithon account at checkout (on by default for Personal, off for Enterprise) and the key is recorded against the buyer's email; signing in with that address then activates whatever computer you are on, and signing out releases it again. A machine that already has a key is asked once, at its first sign-in, whether to bind it; the License Management dialog carries the same tick. A key binds to one account and cannot be moved afterwards, so every place that offers it says so first and asks for a confirmation
Activation now signs you in first: License Management activates through your account, so the server knows who is asking -- which is what lets a key typed there afterwards follow its owner to the next machine. A bound key is no longer accepted by the anonymous endpoint older builds use; those are told to update and sign in
The three-transfer limit is gone: A personal key used to allow one activation and three transfers, spent forever -- reinstall Windows four times and the licence was finished. An unbound key now runs on up to three machines at once, and deactivating one gives the slot straight back. A key bound to an account has no device limit at all: it is live only where its owner is signed in
Headless machines too: spu login --email you@example.com collects whatever the account is licensed for and activates the box; --bind-license claims the key already installed there for that account
Live Sync for every edition: RFC 2217 Server, Live Console, Live Relay and Live Share — and the Remote Serial (RFC 2217) port type — no longer ask for SPU Pro; a free copy uses all of them, and so does a headless spu --invite. What a Pro entitlement changes is the monthly cloud traffic allowance: 10 MB per direction on a free account, 1 GiB with Pro, then purchased traffic packs. The allowance is now enforced — a Live Console or Live Relay session that runs past it stops with quota_exceeded instead of running on. A copy without Pro restores only the RFC 2217 quick shares among its saved bridge links on start-up; the others are kept as saved and come back once Pro does
Live Share — share a port with a colleague who has no account: Live Relay used to require both machines on the same account. Now you can mint a time-limited invite code for one open serial port: Cloud > Share Port with a Guest… lets you pick how long it lasts (1/4/12/24 hours, 12 by default), an optional passcode and a label. Your colleague chooses Remote Serial (Live Relay) and pastes the code or link under "Join with an invite code" — no registration, no subscription, no bound device, with the traffic staying on the sharing side. It is independent of Live Relay in both directions. A share ends when the port closes, when Live Console is switched off, on sign-out and on exit; five wrong passcodes burn the code; an expired code admits no new guest but never cuts a session already in progress
Live Sync state in the status bar: The status bar's Live Sync cell is only an entry point while nothing is running; the moment something is, it gives the name up for the state itself. Amber Shared means a door is open and nobody has come through it (an RFC 2217 listener, an invite code, Live Console or Live Relay switched on); orange bold In use means somebody is driving one of your ports right now — named outright when there is only one of them, as in "Guest: Ann" or "Remote operator"; red Not listening means an RFC 2217 server never got the TCP port it asked for and the link is not working, which until now was said once, in a status message that scrolled away, and never again. RFC 2217 servers count here for the first time: the bar used to tally only cloud shares and relays, so a local RFC 2217 server showed nowhere in it — not while it stood open, not while a remote client was driving the port. Hovering lists all four peers with their own state (which port, which listening port, which guest, since when); clicking opens a menu whose upper half lists everything running with the way to manage each, and whose lower half is still the four switches
Headless machines can mint one too: spu -D /dev/ttyUSB0 --invite prints the code and link, --invite-ttl takes 30m/4h/1d, --invite-passcode-stdin reads a passcode from a pipe, and Ctrl-C revokes the invite on the way out
One-click sharing from the status bar — turn a local serial port into an RFC 2217 server: Exposing a port over RFC 2217 used to take three dialogs: spend a grid slot on a TCP Server pane, open Tools > Bridges, then check every field across a five-tab editor against its defaults. The status bar now has a Live Sync entry that offers three choices: share the port as an RFC 2217 server, switch Live Console on or off, or hand it to a guest (Live Share). The RFC 2217 path asks one question — which TCP port to listen on, with a free one suggested — and optionally which addresses or subnets may connect; everything else takes safe defaults. The network end is a listener built into the bridge, so it spends no grid slot and is not bound by the sixteen-port limit; under Tools > Bridges it shows as TCP :2217 (built-in) and can have its port changed, its traffic watched and its link removed like any other
Guests in a browser — a colleague with nothing installed: Minting an invite now also says what the code opens in a browser: nothing, view only, view and send, or view, send and set the port's parameters (view only by default); a second switch says whether it still opens a Live Relay in the desktop client, which it does by default. The link lands on a page that says which port it names, whose machine it is on, whether the host is online, whether somebody is already on it and whether a passcode is needed; a name and one click later the guest has a terminal for that one port. Headless, --invite-web and --invite-no-relay choose the same two things. The share dialog and the management view show who is watching from a browser
Every guest share in one place: Cloud > Manage Guest Shares… lists the live shares on every machine the account owns, grouped by machine, with the port each code opens and who is on it, and one action: stop it. The list is the server's, not this process's, so a code minted on the laptop in the other room is in it, and ending it here ends it there. It asks only that you are signed in — an owner whose subscription has lapsed can still stop what they started — and it mints nothing
Interface
One naming scheme: The status bar's Live Sync entry lists four peers: RFC 2217 Server, Live Console (formerly Cloud Console), Live Relay (formerly Cloud Relay) and Live Share (formerly Remote Assist). The Cloud menu's Cloud Console and Allow Cloud Relay switches and the Remote Serial (Cloud Relay) port type follow suit; nothing about the features, your settings or your account changes
The bridge badge can close the bridge: The pale-blue (amber while a client is connected) bridge badge above the receive view gains a close button at its right edge. It is hidden by default and appears after a click on the badge; clicking it removes every bridge link this port is part of and says so in the status bar — noticing that a port is bridged and tearing the bridge down are two separate clicks, so it cannot happen by accident. This is also how a quick share is stopped
The status bar shows your username: The account cell at the far right of the status bar used to show the email address you signed in with; it now shows your username — that is what the account is called, and it keeps an address off the screen for anyone looking over your shoulder. The menu it opens and the headless spu login follow suit; the My Account dialog still lists both. An older account with no username still falls back to the email
The licence window, rebuilt: The QR code in License Management is gone — it encoded exactly the URL the button beside it already opened, and on a phone that URL dead-ends: the order form hands back a scan-to-pay image, which nobody can scan with the phone they arrived on. It also showed the WeChat code to English users whose language setting had never been touched. The room it leaves goes to the purchase path, which is its own group at last: a separator, "Don't have a license yet?" and a blue Buy a License… button. The dialog opens at 820×520 rather than 606×364 against a layout that asks for 755×481, and the value column stretches with the pane instead of being pinned wider than it, which had bought a horizontal scrollbar over content with nothing to scroll to
Purchases go to Alithon's own order pages: Register Now and the purchase button in License Management sent non-Chinese users to the old shareit storefront; they now open the WeChat Pay order page for Chinese and the PayPal one for everyone else
Status notices clear themselves, and the account cell opens: A message written to the status bar's left-hand cell used to stay there — "Settings synced" sat through the rest of the session and was rewritten by every scheduled sync — and the cell sat first at zero width, shoving the port status right each time it spoke. Every message now carries a kind (Info, Warning, Error — the colour) and a timeout, and the cell is the bar's elastic middle after the port and traffic cells, so a notice coming or going moves nothing; what does not fit is elided with the whole line on the tooltip. Sync outcomes move to the account they belong to: a scheduled sync that simply worked is silent, and a click on the account cell says who is signed in, when settings last synced, the recent notices newest first, and the account actions
Rx and Tx share one cell: The byte counters in the main window's status bar and in each port's own bar are composed into a single cell
Fixes
Relay errors never reached the caller: The server reports relay failures (port already in use, device not ready) in the same shape as Live Console errors, and they were all handed to the device agent and dropped, leaving the operator side waiting on an answer already given. They are now routed by the request that asked, so a failure says why immediately
A bridged serial port went deaf while nobody was connected: Serving a port over RFC 2217 (or bridging it to a TCP server) stopped that port receiving anything for as long as no client had connected: typing still put bytes on the wire, but the device's answer never appeared, and only removing the bridge brought it back. The first byte from the device was enough — it reached the egress queue, a broadcast to zero clients writes zero bytes, and the bridge read that zero as a transport refusing the frame, so it kept the frame and throttled the source. The throttle stops the read path outright, and both the receive view and the bridge tap read through it. An open sink with nobody connected is now told apart from a refused write: the frame is counted as dropped instead of stalling the queue against a client that may never arrive, and the link's state says "Running, no client connected". Separately, a serial port without RTS/CTS cannot be throttled at all, and such a throttle is now refused — not reading a serial line does not slow the device down, it only loses the bytes in the driver's buffer
Send File / Receive File stayed greyed out after a transfer: After one transfer — finished, failed or cancelled — Send File… and Receive File… in the Connection menu stayed disabled and Cancel Transfer stayed live until the application was restarted. The menu used to be refreshed only when a transfer started; it now follows each port's transfer state and the keyboard focus, so the items come back the moment a transfer ends, and a transfer on one port no longer greys out Send File on another
The licence window told the truth about nothing, and refused keys pasted from an invoice: An install with no licence was told it held a "Personal Edition" one — the check read the enterprise flag, which is false when there is no licence at all, and never asked whether there was one. It says "Not activated" now, and a new Status row answers the question people open the window with: activated, trial with the days left, or expired. There was also no way to remove a licence: the uninstall button's slot has waited since 2017 for a widget the .ui never had, so the button exists now. And the key field refused valid keys — the length gate demanded the 29-character dashed form though the checks strip dashes before counting, the key alphabet is upper case and was compared case-sensitively, and only the ends were trimmed, so a newline from a mail client was fatal. Keys are normalised now and the field shows what was accepted; the two messages it can still refuse with say what is wrong, and one of them was never wrapped in tr(), so a Chinese install got English — twice over the same typo ("licnese")
Relayed keystrokes arrived one character per line, and doubled: A Live Relay carries the remote operator's typing one keystroke per frame, every frame went through the TX-frame echo, and a TX frame opens a display line of its own — so on the owner's screen each character landed on its own line, and against a device that echoes (any interactive console) it landed twice: "uptime" typed by a guest read as six lines of doubled letters. Relayed writes now follow Local Echo, the switch the terminal already has for keystroke-shaped traffic: by default the pane shows only what the device sends back, which is exactly what the guest's own terminal shows, and an owner watching a silent device ticks Local Echo to see the guest's keystrokes. That the port is in someone else's hands is already said by the relay takeover notice
The bottom row of the connection stack was clipped on macOS: Aqua controls paint a few pixels outside the cell the layout books for them, and the stacked pages are clamped flush to the form's size hint with zero margins, so a bottom-row checkbox lost its descenders — visible on the Live Relay and RFC 2217 pages as a cut-off "Keep the remote port's own config". The bleed is now queried from the style and booked as each page's bottom margin; styles without it report zero and are unaffected
Captions on the receive settings page were cut in half: "Tx Time Format" was squeezed to a sixth of its row and read "Tx Time Forma", leaving the two edits 40 px apart; the auto-feed row wants ~740 px of Consolas 11 in a page that opens at 538, so its widest four widgets were cut to 96 px each and read "Auto feed", "Minimal I", "Line Mode". Both blocks are grids now, sharing a caption column, and keep whole captions at the opening size, 300 px wider, and at the dialog's minimum
The account dialog could be clicked again while it waited — and one reply crashed it: Signing in is a round trip to the server, and on a slow link it takes seconds with nothing saying the click landed, so the dialog gets clicked again and every click is another login request. All three buttons now grey the moment one is pressed, the page says what is happening ("Signing in…", "Sending the code…", "Creating the account…"), and the reply or the error gives them back; a 20-second watchdog covers the reply that reaches nobody. Separately, opening a message box from a network reply's own slot is a use-after-free — Qt is still unwinding, and the nested event loop a modal box runs deletes the reply the manager reads again the moment the box closes — so every box a reply asks for now waits for the next turn of the event loop
Status bar popups left their status tip behind: Clicking the Live Sync cell and moving the pointer from Live Console onto one of the popup's own entries sends the clearing tip to the popup, which is a window of its own, so it never reached the main window and the tip stayed in the status bar for the rest of the session, hiding the port status and the traffic counters. Tips landing on a status bar popup are now routed to the window's status bar
Download
| Platform | File |
| --- | --- |
| Windows 10 1809 or later, 64-bit | serial_port_utility_*.exe |
| macOS 12 or later, Apple Silicon | SerialPortUtility-*.dmg |
| Linux x86_64 (Ubuntu 22.04 or later) | serial-port-utility-*-linux-x86_64.tar.gz |
First-launch notes for each platform — Gatekeeper on macOS, the runtime libraries on Linux —
are in the README.
Cloud Relay — use a serial port on another computer: The site machine turns on Cloud > Allow Cloud Relay; the operator picks Remote Serial (Cloud Relay) in the port list, chooses a port on one of the account's online computers and presses connect — from there it behaves like a local port: baud rate, data bits, parity, stop bits, flow control and DTR/RTS can be set remotely, the remote CTS/DSR/RI/DCD states are shown, and X/YMODEM transfers and Modbus work as usual. Both ends need nothing more than outbound Internet access — no public address, port forwarding or VPN. The picker says whether each computer is online and whether relay is allowed there; a port accepts one relay session at a time, the sharing side shows a status line while its port is in remote use, and a dropped relay is never redialled silently — connect again deliberately. Relayed traffic draws on the account's cloud traffic quota
Remote use of a bridged port is visible on the sharing side: A bridge port served over RFC 2217 or plain TCP now announces clients arriving and leaving, the pane badge reads "in use by " and turns amber, and the serial parameters or control lines a remote client sets are logged line by line — the same rule Cloud Relay follows: a port driven from somewhere else must say so
Interface
Remote serial shows what the remote is running: With "Keep the remote port's own config" ticked on the RFC 2217 and Cloud Relay pages, the five greyed-out local parameter rows are hidden — a disabled "115200" was too easy to read as a fact about the remote — and a read-only "Remote now" row shows the baud rate, data format, flow control and server signature the remote actually reports
Cloud menu grouping: The Cloud Console master switch and the three Allow… consents are grouped, and the consents are disabled while the console is off — they all ride the Cloud Console channel, which the flat menu made look independent
Fixes
Log written to a file called NULL: Until the first successful open the log file name is only a placeholder, and flushes triggered by pause, stop or a port opened by the reconnect supervisor did not recognise it, creating a file literally named "NULL" in the working directory. Those flushes now resolve the configured file name template first and log to the right file
DTR lamp stuck grey: After selecting RFC 2217 or Cloud Relay in the connection editor and switching back to a local port, the DTR lamp stayed grey — which reads as "not asserted" — while RTS recovered; both now return to green
DTR/RTS lamps grey for the life of an RFC 2217 client connection: With "Keep the remote port's own config" ticked the client never set DTR or RTS, so the server had nothing to confirm and both lamps showed "never asked" throughout. The first settings sync now queries the remote's current levels, so the confirmed state shows in both RFC 2217 client and Cloud Relay modes
Command latency on the Cloud Console HTTP fallback: When the backend offers no WebSocket channel, queued commands now ride the heartbeat reply, cutting the worst-case wait from 30 seconds to one 20-second beat; a missing or stale cloud snapshot is re-uploaded as soon as the server asks for it, so picking a relay target no longer waits out a snapshot round trip
Download
| Platform | File |
| --- | --- |
| Windows 10 1809 or later, 64-bit | serial_port_utility_*.exe |
| macOS 12 or later, Apple Silicon | SerialPortUtility-*.dmg |
| Linux x86_64 (Ubuntu 22.04 or later) | serial-port-utility-*-linux-x86_64.tar.gz |
First-launch notes for each platform — Gatekeeper on macOS, the runtime libraries on Linux —
are in the README.
等宽字体缺失导致的列错位: 收发视图指定的 Monaco 在 macOS 之外并不存在（此前只替换了 Windows 的 Consolas），缺失时会退化成比例字体，HEX 与时间戳列随之错位；现在两种字体缺失时都会替换为系统等宽字体
Microsoft Store 版本缺少在线服务: MSIX 打包此前会把账户登录、云同步与云控制台整体编译掉，商店版本因此没有这些功能，现已与直接下载的版本一致
English
Features
Local echo: Terminal passthrough now echoes what you type in the receive view, so a device that never echoes back — common on embedded targets — no longer leaves you typing blind. It is separate from Display Send, which shows and logs whole frames from the send box: local echo renders keystrokes in place, in typing order, and keeps them out of the log. Off by default, since a device that does echo would otherwise double every character
Indicator lights toggle: The quick-settings panel can now hide the TX/RX and control-line indicators and give the space back to the data views
Cloud Console live channel: The cloud console now carries commands and status over a WebSocket instead of polling, removing the poll-interval delay. A backend that does not advertise the gateway keeps working on the previous HTTP polling path
Interface
The quick-settings bar drags narrower: Its minimum width used to follow the longest port name, the longest combo entry and the widest label all at once, pinning the bar near 300 pixels. Long combo entries now elide in place — the popup still shows them in full — and the shared label column stops growing, so the bar goes as narrow as you need it
Consistent settings terminology: Options… is now Settings… in the main window and the multi-port dialog, the terminal's connection, receive and send settings read consistently, and the settings panel's Options group is named Log Behavior after what it actually holds
Fixes
Misaligned columns from a missing monospace font: The receive and send views name Monaco, which does not exist outside macOS — only Windows' Consolas was substituted before — so those views fell back to a proportional face and the HEX and timestamp columns drifted out of line. Both families now substitute to the system monospace font when they are missing
Online services missing from Microsoft Store builds: MSIX packaging compiled out account sign-in, cloud sync and the cloud console entirely, so the Store build shipped without them. It now matches the direct download
Download
| Platform | File |
| --- | --- |
| Windows 10 1809 or later, 64-bit | serial_port_utility_*.exe |
| macOS 12 or later, Apple Silicon | SerialPortUtility-*.dmg |
| Linux x86_64 (Ubuntu 22.04 or later) | serial-port-utility-*-linux-x86_64.tar.gz |
First-launch notes for each platform — Gatekeeper on macOS, the runtime libraries on Linux —
are in the README.
X/YMODEM file transfer: Send and receive files over an established serial, TCP or RFC 2217 connection with XMODEM, XMODEM-CRC, XMODEM-1K, YMODEM and YMODEM-G. Protocol traffic is isolated from ordinary terminal data, while a non-modal progress bar reports the file, progress, rate, ETA and retry count. TCP servers can pin a selected client, so remote firmware updates no longer require another terminal application
Single-connection RFC 2217 remote serial: RFC 2217 is now available directly in the port list for connecting to Moxa NPort, ser2net or another Serial Port Utility and setting remote baud rate, data bits, parity, stop bits, flow control and DTR/RTS in the same connection. The device server's existing configuration is preserved by default; parameters are sent only after the user explicitly takes control. Peers without RFC 2217 support warn and degrade safely
RFC 2217 bridge client mode: A bridge can dial a device server and synchronize its serial parameters from the link's other endpoint. Parameters are sent once negotiation succeeds and only changes are sent afterward; remote replies are recorded in the link messages but never applied back to the local serial port
Remote control-line status: RFC 2217 connections show the remote CTS, DSR, RI and DCD states, making hardware handshaking behind a device server directly observable
Fixes
RFC 2217 negotiation: The access server now answers a client's WILL with DO. It previously worked only with clients that also send DO, such as pyserial; a client that opens with WILL alone waited until it timed out and fell back to a plain socket
RFC 2217 negotiation no longer ping-pongs: Answers are tracked per option and sent only when they change something. Two Serial Port Utility bridges pointed at each other used to exchange WILL/DO forever
RFC 2217 compatibility: COM-PORT-OPTION refusals are now interpreted by role, fixing parameter delivery after negotiation with ser2net
Terminal passthrough on network connections: Fixed keyboard passthrough checking only the local serial handle, which made typing ineffective on TCP, UDP and RFC 2217 connections
Bridge peer events: A peer arriving on the device end no longer opens a negotiation with the network end
Download
| Platform | File |
| --- | --- |
| Windows 10 1809 or later, 64-bit | serial_port_utility_*.exe |
| macOS 12 or later, Apple Silicon | SerialPortUtility-*.dmg |
| Linux x86_64 (Ubuntu 22.04 or later) | serial-port-utility-*-linux-x86_64.tar.gz |
First-launch notes for each platform — Gatekeeper on macOS, the runtime libraries on Linux —
are in the README.
Connection activity lamps: The connection group gains interactive TX/RX and control-line indicator lamps that blink to reflect live traffic and control-line state; the classic control-line UI is retired in favour of the lamps
Serial control lines: Added serial control line handling with a new Control Lines tab in the settings dialog
Modbus request builder: Added a Modbus request builder to the Tools menu
Per-field quick settings: Quick settings are now available per field across all groups, with the picker moved into the settings dialog
Line Ending combo: Replaced the send auto-feed checkbox with a Line Ending combo
Restore last connection: Automatically restores the connection that was open at last exit
Terminal caret & honest Tx metrics: The terminal mode shows a caret and reports real Tx counts
UI Improvements
TCP/UDP mode UI: Silenced the server-error popup and polished the TCP/UDP mode UI
Toolbar: Reworked the log-recording and quick-settings toolbar controls
UI alignment & polish: Unified the receive Auto FL and send Loop rows, aligned the Line Ending and Append Checksum combos, and more
Fixes & Enhancements
Settings defaults: Seeded and guarded the remaining Log/Display defaults in the settings panel; never store empty Rx/Tx time formats
.spu session loading: Parse .spu bool flags with toBool so saved true values survive reload
Internationalization: Label the format radios Text, not ASCII, in Chinese
Log directory: Create the log directory before opening the log file