Radio Modems & Wireless Communication

Overview

Radio modems (cee_radio) allow computers to communicate wirelessly over the air using channels, frequencies, and antennas. Modems are split into roles (tx for transmitting, rx for receiving) depending on their physical wiring. A computer never hears its own transmissions unless loopback is enabled in the configuration.

Hardware & Wiring Rules

Roles: A modem is tx when a TX antenna is wired to its signal-out; otherwise, it defaults to rx.
Physical Layout: Two modems fit in a single block, each occupying a separate half (upright or laid flat). Wrenching or breaking them affects only the targeted modem.
Data Flow Wiring: Wire modems according to the data path:
Transmitter: Computer -> in, TX Antennas -> out.
Receiver: RX Antennas -> in, Computer -> out.
Power: Modems, TX antennas, and RX antennas all require proper power and correct polarity. Level 0 is completely silent. Range is determined entirely by the sending transmitter's power level, height, and obstacles.

API Reference Table

Method Signature	Arguments & Types	Description
`r.setChannel(channel)`	`channel` (number 0–6000)	Sets the radio channel frequency.
`r.setLevel(level)`	`level` (number)	Sets the transmission power level (range/strength).
`r.transmit(msg)`	`msg` (table/string)	Transmits a payload over the air; returns the number of accepted arrivals.
`r.getRole()`	None	Returns `'tx'` or `'rx'` based on physical antenna wiring.
`r.canTransmit()`	None	Returns `true` while the modem and its TX antenna are powered and ready.
`r.hasTransmitter()`	None	Alias for `canTransmit()`.
`r.getLastError()`	None	Returns `nil` on success, or an error string (e.g., `'unpowered'`, `'rate_limited'`, `'no_receiver'`) on failure.
`r.isOn()`	None	Returns `true` if the modem's physical power switch is turned on.
`r.publish(key, value)`	`key`, `value`	Continuously publishes state data over the air (newest-value-wins queue system).
`r.readState(id, key)`	`id`, `key`	Reads the latest published state value from a specific sender.

Wireless Events

cee_radio_message
Triggered when a wireless message arrives.
Event returns: _, channel, senderId, message, distance, signalMargin.
cee_radio_state
Triggered when a published state updates over the air.
Event returns: _, channel, senderId, key, value, distance, signalMargin.

Code Examples

Sending a Wireless Message

local r = peripheral.find("cee_radio")
if r then
    r.setChannel(1234)
    r.setLevel(16)
    local sentCount = r.transmit({ hello = "world" })
    print("Message sent to " .. sentCount .. " receivers.")
end