Markers & port codes

This page explains what EEG triggers and port codes are, the ways SMACC can send them, and how to configure each one. If you just want the steps, jump to Configuring trigger output in SMACC.

What are port codes and triggers?

When you run a sleep or dream study you want to know exactly when things happened — a cue played, REM was observed, a dream report began — and line those moments up with the EEG recording. The standard way to do this is a trigger: at the instant of an event, the stimulus computer sends a small number to the EEG amplifier, which records it on a dedicated trigger channel alongside the brain signal. That number is the port code (also called an event marker or trigger code). During analysis you find events by their code — e.g. “every 41 is an observed REM onset.”

A port code is an 8-bit value, so it is always an integer from 1 to 255. That range follows from the hardware: a trigger is physically eight on/off lines (eight bits), and the amplifier reads them as one byte. SMACC keeps every code inside 1–255 for this reason. See Configuring codes for how to view and edit which event sends which code.

Terminology

The words event, marker, trigger, and port code get used loosely in the field; SMACC uses each one for exactly one thing, in the UI, the docs, and the session log:

Term	Meaning in SMACC
Event	A named thing that can happen during a session — a cue started, REM observed, lights off. Each is an entry in the study’s event registry, with a label and a port code.
Marker	The durable record produced when an event fires. A marker is always a log line; if the event is routed to a transport, it also carries the port code there.
Port code	The 8-bit number (1–255) identifying an event on the amplifier’s trigger channel. Also called a trigger code.
Trigger	The act of sending a port code over a transport. An event can be logged without being triggered.
Transport	A path that carries the code to the recording: the LSL marker stream, or a hardware TTL line (serial trigger box / parallel port).
Log level	The severity tag on a log line (DEBUG…CRITICAL). The log file records every level; levels only filter the live preview. See log levels.

Default event codes

These are SMACC’s built-in event markers and their default port codes — the out-of-the-box event_codes registry. A study can retune any code in the Markers window; the change travels in its .smacc and is written into every session log.

Code	Event	Key	Notes
41	REM detected	REMDetected	sleep-stage observation (keypad 4 in the Event logging window)
42	Tech in room	TechInRoom
43	Training start	TrainingStart	start of a training/learning phase (TMR cue learning, TLR practice)
44	Training end	TrainingEnd
45	Signal observed	SignalObserved	a lucidity/communication signal; the signal type + confidence are logged as the detail
46	Sleep onset	SleepOnset
47	Lights off	LightsOff
48	Lights on	LightsOn
49	Clapper	Clapper	sync marker
50	Note	Note
51	Start recording	RecordingStarted	sets the reference clock for dream-report timestamps
52	Wake detected	WakeDetected	sleep-stage observation (keypad 0 in the Event logging window)
53	N1 detected	N1Detected	sleep-stage observation (keypad 1)
54	N2 detected	N2Detected	sleep-stage observation (keypad 2)
55	N3 detected	N3Detected	sleep-stage observation (keypad 3)
56	Arousal detected	ArousalDetected	a brief transient arousal (distinct from a sustained Wake)
57	Artifact detected	ArtifactDetected	EEG artifact (movement, electrode noise, etc.)
60	Cue started	CueStarted
61	Cue stopped	CueStopped
62	Noise started	NoiseStarted
63	Noise stopped	NoiseStopped
64	Intercom started	IntercomStarted
65	Intercom stopped	IntercomStopped
66	Visual started	VisualStarted
67	Survey opened	SurveyOpened
68	Visual stopped	VisualStopped	the light is actually off (pairs with 66)
69	Chat to participant	ChatMessageSent	typed intercom message; log-only by default
70	Chat from participant	ChatMessageReceived	participant’s typed reply; log-only by default
71	Survey submitted	SurveySubmitted	in-app survey responses saved; log-only by default
100	SMACC initialized	TriggerInitialization	startup connection test; not a stimulus marker
105	Biocal sequence started	BiocalSequenceStarted	brackets a played biocal sequence
106	Biocal sequence stopped	BiocalSequenceStopped	completed or aborted
107	Biocal cancelled	BiocalCancelled	shared; the preceding start code identifies the biocal
108	Biocal completed	BiocalCompleted	shared; the task window ran out
110	Biocal: Eyes Open	BiocalEyesOpen	biocal starts mark the task-window opening
111	Biocal: Eyes Closed	BiocalEyesClosed
112	Biocal: Look L/R	BiocalLookLR
113	Biocal: Look U/D	BiocalLookUD
114	Biocal: Blink	BiocalBlink
115	Biocal: Clench Jaw	BiocalClenchJaw
116	Biocal: Flex Feet	BiocalFlexFeet
117	Biocal: Hold Breath	BiocalHoldBreath
118	Biocal: Breathe	BiocalBreathe
119	Biocal: Rest	BiocalRest
120	Biocal: LRLR Open	BiocalLRLROpen
121	Biocal: LRLR Closed	BiocalLRLRClosed
122	Biocal: LRLR Slow	BiocalLRLRSlow
123	Biocal: Fist Clench	BiocalFistClench
124	Biocal: Fist Closed	BiocalFistClosed
125	Biocal: Sniff Open	BiocalSniffOpen
126	Biocal: Sniff Closed	BiocalSniffClosed
200	Dream report stopped	DreamReportStopped
201	Dream report started	DreamReportStarted	increments per report (201, 202, …)

Codes are integers in 1–255 and must be unique among events routed to a transport (LSL or TTL).

Configuring codes

Open the Markers window from the Panels column (in a Session or in the Editor). It is the home for everything about event signaling: a routing legend (what the log file, the live preview, LSL, and TTL each receive, and which switch governs it), the full event registry grouped by category (including the events with no grid button — lights, panel controls, biocals, chat, system), and the hardware TTL transport. For each event you can set:

• Code — the 8-bit port code (1–255) sent when the event triggers.
• LSL — whether a firing sends the code over the LSL marker stream.
• TTL — whether a firing sends the code over the hardware TTL trigger. The column is grayed out until a transport is enabled in the window’s Hardware TTL transport section (the ticks are kept and re-arm with it). An event with neither LSL nor TTL ticked is log-only.
• Preview — whether the event shows in the live log preview. The session log file always records every event regardless; this only controls the on-screen preview.
• Increment — give an event a unique, increasing code on each firing (for example dream reports: 201, 202, 203, …) so individual occurrences are findable in the trigger channel. Off uses one fixed code each time.

TTL safe max code raises a soft warning for TTL-routed codes above it, handy when your trigger hardware accepts only a limited range (some older systems do; LSL carries any code). Codes must be unique among routed events and within 1–255; the window blocks anything else.

Custom events. Use Add event… — in the Event logging panel itself, or in the Markers window — to create your own button events (a label and a code). They appear in the Event logging panel alongside the built-ins and can be removed again with the Markers window’s Remove. Built-in events can be retuned but not removed or renamed.

Edits are staged until you press Apply (which validates them first); Revert re-reads the session’s current setup. The window stays available throughout a session. If you change a code mid-session, the change is written to the log with a timestamp, so the code-to-event mapping for that session is always recoverable.

Beyond port codes, SMACC logs the important interactions too — volume, colour, device, and fade changes — as plain log lines (no port code), so the session record is complete.

Event logging panel

The manual event buttons (the sleep-stage family, Signal observed, Sleep onset, Note, your custom events, and so on) live in the Event logging panel — open it from the Session window’s Panels column. The sleep-stage buttons take a fixed keypad — 0 Wake, 1 N1, 2 N2, 3 N3, 4 REM — and the remaining buttons take 5–9 in order; the shortcuts are active while the panel is focused. The Lights toggle stays on the main window (it also flips the dark theme).

Signal observed. One button covers every lucidity/communication signal a study uses (LRLR, sniff, facial, …), so you do not need a separate button per signal. Pick the signal type (the box is editable — type your own and it is remembered for the rest of the session) and a confidence (certain / probable / possible) beside the button. Pressing it fires the marker immediately and logs your selection as the detail, so the marker’s timing tracks the observation. Confidence is recorded as a comment; it never changes whether the marker reaches the EEG.

Where codes live

Your codes are saved in the SMACC file (so they travel with it) and written into every session .log (both the initial and final settings blocks), so any session is self-documenting: you can decode its markers later even if the codes changed mid-session.

How SMACC sends triggers

SMACC emits markers over LSL (Lab Streaming Layer), a network marker stream. On top of that, you can optionally enable one hardware transport so a physical trigger reaches an amplifier that doesn’t read LSL. Both fire from the same place, and each event routes to either path independently: its LSL and TTL flags in the registry decide where its code goes (both by default; an event routed to neither is log-only).

Transport	What it is	What you need
LSL (always on)	A network marker stream recorded by an LSL-aware recorder (e.g. LabRecorder → XDF). Works on the same computer or across the network.	Nothing extra.
Serial (USB trigger box)	The modern replacement for the parallel port. The box appears as a COM port; SMACC writes the code as one byte and the box mirrors it onto 8 TTL lines.	A USB-serial trigger box and its COM port.
Parallel port (LPT)	The classic 25-pin port. Eight data pins carry the code byte, sampled by the amplifier.	An LPT port (often an add-in card) and the InpOut32 driver (see below).

NoteLSL stays on

Enabling a hardware transport does not turn LSL off — events routed to both (the default) reach the LSL stream and the hardware line together. The hardware path is purely additional. LSL support ships inside SMACC itself — there is nothing separate to install on the sending side (the recorder, e.g. LabRecorder, is its own program).

TipWhy route per event?

Most studies leave every event on both transports. Per-event routing earns its keep when the TTL hardware is restricted — an older amplifier that only accepts a limited code range can keep its key events on TTL (inside the safe max) while chattier or higher-coded events still reach the LSL stream.

What is the baud rate?

For the serial (USB trigger box) transport you also set a baud rate — the speed, in bits per second, at which SMACC talks to the box over its COM port. It is a property of the serial link, not of the trigger codes: the same 8-bit code (1–255) is sent either way; baud only controls how fast that byte goes out.

The one rule that matters is that both ends must use the same baud rate. Your box is configured (by a switch, firmware, or its manual) to expect a specific rate, and SMACC has to match it — a mismatch produces garbled or missed triggers, not an error.

• Where to find it: check your trigger box’s manual or its configuration utility. Common rates are 9600, 19200, 38400, 57600, 115200, and 230400.
• SMACC’s default is 115200, which many modern USB trigger boxes (e.g. typical BrainProducts/Neurospec-style adapters) use out of the box. If yours specifies a different rate, pick it from the dropdown (or type any other value).
• Higher isn’t “better.” A faster rate shaves only microseconds off a one-byte write, which is negligible next to audio/event timing — so choose the rate your box expects rather than the largest one.

If triggers don’t register, a wrong baud rate is one of the first things to check (alongside the COM port and the pulsed vs. set-and-hold mode).

Pulsed vs. set-and-hold

Amplifiers and trigger boxes differ in how they expect the code to appear on the lines, so SMACC offers two modes:

• Pulsed — SMACC raises the code on the lines, waits a configurable pulse width (e.g. 10 ms), then drops them back to 0. Each event is a brief, distinct pulse. Choose this when the amplifier expects a momentary trigger, or when you want SMACC to control the pulse length.
• Set-and-hold — SMACC writes the code once and leaves it on the lines until the next event. Choose this for amplifiers that sample a held level, and for boxes that generate their own fixed-width pulse when they receive a byte (SMACC just sets the value; the box shapes the pulse).

If you’re not sure which your hardware wants, start with pulsed at 10 ms and verify with the Test button (below); switch to set-and-hold if events don’t register cleanly.

Configuring trigger output in SMACC

1. Open the Markers window from the Panels column (available both in a live Session and in the Editor) and find its Hardware TTL transport section.
2. Tick Enable hardware trigger output.
3. Choose a Transport:
   • Serial — pick your box’s Port from the dropdown (click Refresh if you plugged it in after opening the window) and set the Baud rate to match your box (see What is the baud rate?; SMACC defaults to 115200). If the rig isn’t attached right now, you can type the port name (e.g. COM3) directly.
   • Parallel port — enter the Address as hex (see Finding your parallel-port address).
4. Choose a Mode (pulsed or set-and-hold) and, for pulsed, a Pulse width.
5. Click Test to send one pulse and confirm the amplifier sees it. The result appears next to the button; an error explains what went wrong.
6. Click Apply.

The whole configuration is saved in your SMACC file, so it travels with the rest of your setup. Because a COM port name or LPT address is specific to one computer, SMACC reports a clear error if the saved port can’t be opened on the machine you load it on — re-pick it in the Markers window and save again.

WarningAlways validate on the real hardware

A successful Test confirms SMACC could open the port and write to it. It does not prove the amplifier recorded the correct code on its trigger channel. Before relying on triggers for a study, record a few test events and confirm they appear, with the right codes, in the EEG.

Finding your parallel-port address

A parallel port is addressed by a base I/O address, written in hexadecimal. The most common values are:

• 0x378 — the usual address for the first parallel port (LPT1).
• 0x278 — a common second port (LPT2).
• 0x3BC — older onboard ports.

Add-in PCIe/PCI parallel cards are frequently mapped somewhere else entirely, so don’t assume — look it up:

1. Open Device Manager (press Win+X, then choose Device Manager).
2. Expand Ports (COM & LPT) and double-click your parallel port.
3. Go to the Resources tab and read the first I/O Range — the start of that range is your address. Enter it in SMACC with a 0x prefix (e.g. 0x378).

Installing the InpOut32 driver (parallel port only)

Modern Windows blocks direct port access from ordinary programs, so the parallel-port path needs a small kernel driver, InpOut32 / inpoutx64. SMACC does not download or install it for you (an earlier version did, and it proved fragile and required admin rights every launch). Install it once, manually:

1. Download InpOutBinaries from highrez.co.uk.
2. Run the included InstallDriver.exe once (as administrator) to install the kernel driver.
3. Make sure inpoutx64.dll is where SMACC can load it — on the system path, in C:\Windows\System32, or beside SMACC.exe.

If the driver isn’t available, SMACC’s parallel transport reports a clear error and falls back to LSL only — it never crashes a session over a missing driver.

Verifying

• Use the Test button in the Markers window’s transport section for a quick “can SMACC drive the line?” check.
• Then confirm end-to-end on the amplifier: record a short block, fire a few events from the Event logging window, and check that the codes land on the EEG trigger channel. Only the real recording proves the path works.