Node-bus command reference

Values below include the encoded payload-length bits. CRC is the CRC-8 over the command byte and every following byte except the CRC itself.

Control and metadata

Value	Name	Payload	Description
0x20	MCMD_INIT	none	Initialize/reset protocol state
0x28	MCMD_GET_INFO	none	Read general node information
0x29	MCMD_GET_INFO	variable index	Read one variable's metadata
0x33	MCMD_SET_ADDR	mode, address MSB, LSB	Set node or group address
0x37	MCMD_SET_NAME	extended length, 1–16 name bytes	Set the node name
0x39	MCMD_SET_BAUD	baud code	Change node-bus baud rate
0x41	MCMD_FREEZE	enable (1/0)	Freeze/unfreeze sampled values
0x49	MCMD_SYNC	enable (1/0)	Buffer/release hardware demand updates
0x4E	MCMD_SET_TIME	six BCD bytes	Set real-time clock: DD MM YY HH MM SS
0x50	MCMD_UPGRADE	none	Enter firmware-upgrade mode
0x58–0x5E	MCMD_USER	0–6 user bytes	Node-specific user command
0x61	MCMD_ECHO	one byte	Return the supplied byte
0x68	MCMD_TOKEN	none	Token operation; reserved on node bus
0x70	MCMD_GET_UPTIME	none	Read uptime in seconds

SET_ADDR modes are 1 for the full node address, 2 for only its high byte, and 3 for the group address. Modes 1 and 3 carry a complete 16-bit value. The new address is stored non-volatilely.

Broadcast FREEZE 1 after selecting a group to make members measure and hold their current values; FREEZE 0 ends that mode. With SYNC 1, members retain new demand values in an internal buffer; SYNC 0 applies them to hardware together. These operations provide simultaneous sampling and simultaneous application without requiring colliding replies.

Baud codes

The source defines these values:

Code	bit/s	Code	bit/s
1	2,400	6	38,400
2	4,800	7	57,600
3	9,600	8	115,200
4	19,200	9	172,800
5	28,800	10	345,600

Variable write commands

Value	Name	Wire format after command	Reply
0x80+n	MCMD_WRITE_NA	index, 1–4 value bytes, CRC	none
0x88+n	MCMD_WRITE_ACK	index, 1–4 value bytes, CRC	received CRC
0x98	MCMD_FLASH	CRC	flash confirmation
0xAF	MCMD_WRITE_RANGE	length, first index, last index, packed values, CRC	received CRC

For the fixed-size forms, n is the number of bytes following the command, including the index: n = 2 through 5 for 1–4-byte values. Values are sent most significant byte first. WRITE_NA is the only suitable write for group or broadcast addressing.

WRITE_RANGE writes consecutive variables. The payload is first index, last index, then each variable's bytes in metadata order. Its extended length uses the normal short/long length encoding.

Variable read commands

Value	Name	Payload	Result
0xA1	MCMD_READ	index	One variable
0xA2	MCMD_READ	first index, last index	Consecutive variables

The one-variable response is 0x78 + width for widths 1–4, followed by the value MSB first and CRC. Larger or ranged results use the extended response form described under responses.

Arbitrary memory access

Value	Name	Payload after length	Meaning
0xB7	MCMD_WRITE_MEM	subaddress, 32-bit address, data	Write memory
0xBF	MCMD_READ_MEM	subaddress, 32-bit address	Read memory

The extended payload length for WRITE_MEM is 5 + data size. READ_MEM is exactly:

0xBF 0x07 size-MSB size-LSB subaddress address-MSB address-2 address-3 address-LSB CRC

The 0x07 is the extended payload length; the requested byte count is the 16-bit size field. These operations are intended for firmware transfer and diagnostics, not ordinary node variables.

The high nibble selects the memory region:

Address range	Region
0x0.......	RAM
0x1.......	non-volatile RAM
0x2.......	EEPROM or flash data
0x3.......	program/code space

The exact valid address range and write permissions are device-specific.

Logging

MCMD_LOG is 0xC1 with a one-byte operation:

Operation	Meaning	Response
0	Read log	Extended data response
1	Clear log	0x78, CRC