vRIO — virtual RIO cockpit device

A software replica of the cockpit RIO (Remote Input/Output) board: it opens a COM port and speaks the device side of the RIO serial protocol, so any host that expects the real hardware — most importantly RIOJoy — can talk to it without a cockpit attached.

The window is an interactive version of the cockpit control panel that RIOJoy's profile editor draws (the same functional layout from the original Win32 RIO design: five MFD clusters, four board columns, two keypads, encoder gauges). But where the editor edits bindings, vRIO's cells are the physical controls:

• Left-click a cell — momentary button press (ButtonPressed/Released or KeyPressed/Released on the wire). Right-click — latch it down.
• Drag the X/Y box and the Z / L / R gauges — the five analog axes, returned by the next AnalogReply (14-bit signed, 7-bit-pair packed). Gauges span each axis' realistic hardware travel, not the full 14-bit range: Z/L/R rest at raw 0 at the gauge bottom and travel to −800 (throttle — forward travel runs negative, matching RIOJoy's ratchet) or +500 (spring-loaded pedals), and the stick covers ±80 around center — the windows RIOJoy's calibrator expects.
• Cells shade to the lamp state the host commands (LampRequest: off / dim / bright, with slow/med/fast flash), so RIOJoy's press-feedback lights the on-screen panel just like the real buttons.
• Keyboard and Xbox (XInput) controller input drive the same controls through a bindings file (%APPDATA%\vRIO\bindings.txt, created with commented defaults on first run — Edit bindings… opens it, Reload bindings applies edits live). Keys and pad buttons press any RIO address; pad sticks/triggers and keys drive the axes in each axis' realistic travel window, with deflect (spring-back), rate (throttle-style, position holds), deadzone, and invert options. The default profile makes the controller mandatory: all five axes live on the pad (left stick / triggers / right stick = stick / pedals / throttle) and the keyboard covers the button field — number row + QWERTY row = the upper MFD bank, home + bottom rows = the lower MFD bank (4-key blocks split by an unbound gap key), F1–F6 / F7–F12 = the Secondary / Screen columns, numpad = internal keypad (hex keys on the operators), arrows + Space = hat + main, with ABXY / dpad / shoulders on the pad's named buttons.

Wire behavior

Protocol per riojoy/docs/PROTOCOL.md (9600 8N1, [cmd][payload…][7-bit checksum], ACK 0xFC / NAK 0xFD / RESTART 0xFE / IDLE 0xFF), with device behavior grounded in the real v4.2 firmware dump (riojoy/rio-firmware/RIOv4_2-ANALYSIS.md):

• ACKs every well-formed packet; NAKs bad-checksum packets.
• TX is paced at the wire rate — one byte per 10-bit frame (~1.04 ms at 9600 8N1), never closer. A virtual null-modem has no UART, so unpaced writes would land at the host in microsecond bursts no real board could produce; vRIO's writer thread schedules each byte against a monotonic slot deadline instead, so e.g. the 51-byte CheckRequest response takes the same ~53 ms it takes real hardware.
• CheckRequest → the real board's init handshake: TestModeChange enter, one BoardOk CheckReply per board (the 11 boards from the legacy firmware's table), then TestModeChange exit. Hosts wait (≤5 s per step) on both test-mode packets and send nothing while test mode is active, so the exit is mandatory. VersionRequest → configurable version, default 4.2.
• ResetRequest re-zeroes the targeted axis (or all).
• A NAK re-sends the last event up to 4 times, then gives up with a RESTART byte — the real board's retry budget.
• Optional v4.2 reply-wedge emulation: after retry exhaustion (or the "Wedge analog now" button), analog requests are silently dropped — still ACK'd, RX path alive — until a host ResetRequest, reproducing the latch-leak fault the firmware analysis documents. Use it to exercise RIOJoy's 5-second no-analog recovery watchdog.

Using it with RIOJoy on one PC

The two apps need a crossed serial link. Install a com0com virtual null-modem pair (e.g. COM5 ⇄ COM6), then:

1. Run VRio.App, pick COM5, Open.
2. Point RIOJoy at COM6.

RIOJoy's DTR open-pulse shows up in the wire log (DSR handshake), its ~55 ms analog polling drives the "analog polls served" counter, and every click on the vRIO panel arrives at RIOJoy as real cockpit input. Two physical PCs with a null-modem cable work the same way.

Repository layout

Path	Contents
src/VRio.Core	Protocol framing/builder/parser, the VRioDevice state machine, serial pump, panel layout data (class library)
src/VRio.App	WinForms panel UI
tests/VRio.Core.Tests	xUnit tests for the protocol + device engine

Building

Same toolchain as RIOJoy: .NET SDK (8.0+) with the .NET Framework 4.8 targeting pack; apps target net48 so deployed builds run in-box on Windows 10/11.

dotnet build VRio.sln -c Release
dotnet test VRio.sln

Interop is additionally verified against RIOJoy's real RioSerialLink (version/check/analog/lamp/button/keypad/reset round-trips over an in-memory transport) — see the RIOJoy repo for the host side.