State Machine

Internal state machine of the MD driver is compliant with industrial CIA402 standard, and allows for precise state control and validation.

However for most applications, such level of control can introduce complication rather than functionality, thus we will first describe simplified model, and later full model, for those who require it.

MD Protocol model

Note

This section is applicable while operating MD using MD Protocol.

While internally the state machine is transitioning though states as CIA402 requires, most of those changes happen in a span of micro-seconds, and are not very important from user perspective.

Transition	Description	Example
< 0 >	Disable by user	CANdleSDK: MD::disable(); MD Protocol: Write (hex) 0x40 to state (0x142) register
< 1 >	Enable by user	CANdleSDK: MD::enable(); MD Protocol: Write (hex) 0x27 to state (0x142) register
< 2 >	Non-critical error	Position/Velocity limit hit; CAN communication loss
< 3 >	Velocity reached zero	-
< 4 >	All errors cleared	CANdleSDK: MD::clearErrors()

Full State Machine model

Note

This section is applicable while operating MD using CANOpen Protocol.

The state machine is defined according to CIA402 specification as follows:

All the transitions are based on the control word. The current state can be read using the status word (0x6041)

Command	Reset Fault (bit 7)	Enable Operation (bit 3)	Quick Stop (bit 2)	Disable Voltage (bit 1)	Switch On (bit 0)	Decimal Value
Shutdown	0	X	1	1	0	6
Switch On	0	0	1	1	1	7
Switch On and Enable Operation	0	1	1	1	1	15
Disable Voltage	0	X	X	0	X	0
Quick Stop	0	X	0	1	X	2
Disable Operation	0	0	1	1	1	7
Enable Operation	0	1	1	1	1	15
Fault Reset	0→1	X	X	X	X	128

Table 1: State machine control word description.

X means “do not care”

Example:

To put the drive into operational mode set:

1. Control word = 6 (dec) (Shutdown cmd)

2. Control word = 15 (dec) (Switch on and Enable Operation cmds)

The events and respective transitions are gathered in the table below:

Transition	Event	Internal Action
0	Automatic transition after power up	Drive internal initialization
1	Automatic transition after drives internal initialization	Object dictionary is initialized with NVM data
2	Shutdown command received	None
3	Switch on command received	None
4	Enable operation command received	Current controllers are on, power is applied to the motor
5	Disable operation command received	Current controllers are off, power is not applied to the motor
6	Shutdown command received	Current controllers are turned off
7	Quick stop command received	Current controllers are turned off
8	Shutdown command received	Current controllers are turned off
9	Disable voltage command received	Current controllers are turned off
10	Disable voltage / Quick stop command received	Current controllers are turned off
11	Quick stop command received	Quick stop action is enabled. The drive decelerates and transits to SWITCH ON DISABLED
12	Automatic transition when quick stop is completed	Current controllers are turned off
13	Fault occurred	Current controllers are turned off
14	Automatic transition to fault state	None
15	Fault reset command received	Fault is cleared if not critical

Table 2: State machine transitions description.

0x6041 – Statusword

Describes the current state of the internal CiA402 state machine implemented on the drive.

Entry table

Name	Index:Sub	Type	Bit Size	Default Data	Min Data	Max Data	Unit	SDO	PDO
Statusword	0x6041:0	UNSIGNED16	16	0	—	—	—	RO	Tx

Status Word	State Machine State
xxxx xxxx x0xx 0000	Not Ready to Switch On
xxxx xxxx x1xx 0000	Switch On Disabled
xxxx xxxx x01x 0001	Ready to Switch On
xxxx xxxx x01x 0011	Switched On
xxxx xxxx x01x 0111	Operation Enabled
xxxx xxxx x00x 0111	Quick Stop Active
xxxx xxxx x0xx 1111	Fault Reaction Active
xxxx xxxx x0xx 1000	Quick Stop Active

Table 3: State machine status word description.

Bit 10 of the statusword indicates the current target has been reached (1) or not (0). This bit is motion mode - dependent, meaning for example in position mode it indicates the position has been reached (within a 0x6067 Position Window margin), and in velocity mode that a velocity target has been reached (within 0x606D Velocity Window).

Bit 11 of the Statusword indicates whether any of the internal limits was active during current power up - for more information on which limit is active, check the 0x2003:7 Motion Status.