Simulated TrueForce

Simulated TrueForce

Quick reminder of the difference: force feedback is the physical force you feel through the wheel (weight, road pull, kerbs), and it works with no setup. TrueForce is Logitech's extra layer of fine, fast vibration and texture on top; some games build it in, and this page is about adding it to the games that do not. Full explainer in Force Feedback in Games.

TrueForce is normally provided by the game itself through Logitech's TrueForce support (see Force Feedback in Games). For titles with no built-in TrueForce, this project ships logi-tf-sim: a small background helper that builds engine haptics from the game's own live data (engine RPM, speed, throttle, sent over the local network) and plays them through the wheel's real TrueForce audio path. That same live data drives the wheel's rev-light strip as a live RPM display.

On the G923 this is the only TrueForce there is: Logitech's own TrueForce files do not work for it on Linux (see G923), so the helper is the supported path. It finds a G923 automatically and streams to the wheel's own TrueForce interface, mirroring the live force-feedback output into the stream so haptics and force feedback agree instead of fighting.

What you feel

An engine note through the wheel rim: a fundamental tone at the engine's firing rate plus harmonics, louder with throttle, present at idle, silent when the engine is off. The rev LEDs fill with RPM (on the RS50 using your active LIGHTSYNC slot's colors and direction; on a real G PRO rim the onboard profile owns the colors). On a G923 the helper drives the five LED pairs of the strip directly (they are also standard Linux LEDs, see G923).

Supported games

Any game that broadcasts its live data in one of these formats:

Format	Default port	Games
Codemasters / EA float array	20777	DiRT Rally 2.0, DiRT 4 and the classic Codemasters format titles
Project CARS 2	5606	Project CARS 2, Automobilista 2
Modern EA F1	20777	F1 22 through F1 25
EA Sports WRC	20777	EA Sports WRC
OutGauge	4444	BeamNG.drive

The helper listens on all of those at once, quietly, and detects the game from the packets themselves; every port can be changed. It also accepts a small relay protocol (port 20780) for the sims that publish telemetry into Windows shared memory instead of broadcasting it: iRacing, RaceRoom, Assetto Corsa, Competizione, EVO, rFactor 2 and Le Mans Ultimate. Those need logi-tf-relay running inside the game's Proton prefix to feed it. Since 0.29.0 the relay is written and attached to each release as a download; see Simulated TrueForce Internals and docs/SHARED_MEMORY_RELAY.md.

Euro Truck Simulator 2 and American Truck Simulator are a third case: they publish through a plugin interface, so a native Linux plugin (liblogi_tf_scs.so, also a release download) forwards their telemetry. No Wine involved.

Playing something else that sends UDP telemetry? See Add a Game for how to capture it and help get it added.

Enabling it, per game

1. Open the Setup page in logi-wheel-gui or logi-wheel (see Configuring the Wheel) and find the Simulated TrueForce panel: master switch, helper start/stop, and a per-game list with individual enables and intensities.
2. Switch on the game's own telemetry setting. Examples:
   • DiRT Rally 2.0: hardware_settings_config.xml, set <udp enabled="true" ...> (the stock port 20777 is the default here too).
   • Automobilista 2 / Project CARS 2: System settings, UDP frequency to a nonzero value, protocol "Project CARS 2".
3. Race. The helper stays silent until the game's data arrives and stops when it goes quiet.

The knobs

Configuration lives in ~/.config/logi-wheel/tf-sim.conf (or $XDG_CONFIG_HOME/logi-wheel/ if you set that; plain key=value, and the Setup page edits it for you):

Key	Meaning	Default
enabled	master switch	on
intensity	master intensity, 0-100	30
pitch	felt rev rate, 10-200 percent. 100 puts the fundamental at the crank rate (rpm/60 Hz); lower feels like a slower, heavier engine	35
cylinders	cylinder count, used to derive the firing rate the note is built from	4
effects	mix in the haptic layers beyond the engine note (kerbs, surface, rev limiter and the rest); off is engine-only	on
leds	drive the rev-light display from telemetry RPM	on
wheel	which attached wheel to drive: auto, dd (RS50 or G PRO) or g923. rs50, gpro and 923 are accepted too	auto
port.codemasters (also serves F1 and EA Sports WRC), port.pcars, port.beamng, port.relay	the ports it listens on	20777 / 5606 / 4444 / 20780
game.<id>.enabled, game.<id>.intensity	per-game override, applied on top of the master	on / 100
g923.ffb_invert	G923 only: sign of the mirrored force-feedback value in the stream (hardware-calibrated; leave alone unless forces and haptics visibly disagree)	1

Intensity is master x per-game, so you can set a global comfort level and trim individual games. Pitch is the one to play with if the engine feel reads too frantic or too lazy: it scales the fundamental frequency without touching amplitude.

Wheel only matters on a rig with more than one wheel plugged in. auto takes a G923 whenever it finds one, which is right for a single wheel and wrong for a rig with a G923 and a direct-drive wheel together: the direct-drive wheel is never reached, because the search stops at the G923. Setting wheel to dd or g923 says which one you meant. Both apps offer it on the Setup page, so you should not need to edit the file.

For a one-off run without changing your configuration, LOGI_TF_SIM_WHEEL takes the same values and wins over the file.

Trying it without a game

The Setup page (and logi-tf-sim --sweep from a terminal) offers a consent-gated test sweep: a synthetic RPM run-up so you can feel the effect and calibrate intensity with no game running. Hold the rim first; it is a direct-drive wheel.

Good to know

• Simulated TrueForce and games with built-in TrueForce do not fight: the helper only plays while the game's data is flowing, and games with native TrueForce support stream their own effects directly without using the simulation.
• The rev-light feeder runs at G HUB's own cadence (~60 Hz), writing only when the level actually changes, so a rev sweep keeps up with the engine; see Simulated TrueForce Internals.
• The helper plays through libtrueforce, the project's own version of Logitech's TrueForce support.

For how it works inside (parsers, synthesis, the watchdog loop), see Simulated TrueForce Internals.