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8540_en_03 PHOENIX CONTACT 20
13 EtherCAT
®
State Machine: AL Objects
The device has a state machine, called the EtherCAT
®
State Machine (ESM).
The EtherCAT
®
master sends state change requests to the AL control register of the slave. The slave displays the current
state in the AL status register and make additional error codes available in the AL status code register in the event of errors.
13.1 AL control and AL status register
If the master writes to the AL control register, then the corresponding state transition is triggered in the device state machine
by the slave. The AL status register reflects the current state of the slave.
Index
(hex)
Object
name
Data type Rights Meaning/value
0120 AL Control UINT16 R/W Bit 0 ... bit 3 State (AL status requested by master)
01
hex
= Init (I)
02
hex
= Pre-Operational (P)
03
hex
= Bootstrap (B)
04
hex
= Safe-Operational (S)
08
hex
= Operational (O)
Bit 4 Acknowledge (Master acknowledge bit)
00
hex
= Parameter Change of the AL Status Register will be un-
changed.
01
hex
= Parameter Change of the AL Status Register will be re-
set.
Bit 5 ... bit 7 Reserved
00
hex
= Shall be zero
0130 AL Status UINT16 RO Bit 0 ... bit 3 AL Status (AL status requested by master)
01
hex
= Init (I)
02
hex
= Pre-Operational (P)
03
hex
= Bootstrap (B)
04
hex
= Safe-Operational (S)
08
hex
= Operational (O)
Bit 4 Change (Error Flag, Master acknowledge bit)
00
hex
= Confirmation of state in AL Control Register
01
hex
= A change has happened or an error occurred.
Bit 5 ... bit 7 Reserved
Bit 8 ... bit 15 Application Specific
Reserved
0134 AL Status
Code
UINT16 RO Bit 0 ... bit 15 All Status Code (send by slave)
