flexi-bot/docs/marlin/_gcode/M261.md

tag	title	brief	author	requires	group	codes	notes	parameters	examples
m0261	I2C Request	Request and echo bytes from the I2C bus.	thinkyhead	EXPERIMENTAL_I2CBUS	i2c	M261	Requires `EXPERIMENTAL_I2CBUS`.	tag optional description values A false The bus address to request bytes from tag type addr byte tag optional description values B false The number of bytes to request tag type count byte tag optional since description values S true 2.0.9.3 Output style. Default is 0 (raw echo) if nothing else is given. tag type description 0 style Raw echo tag description type 1 Bytes (hex) style tag description type 2 1 or 2 byte value (decimal) style tag description type 3 Bytes (decimal) style

Request bytes from the I2C bus and echo them to the host. To find out how to do more useful things with I2C see the I2C master / slave article.