BECKHOFF EtherCAT Registers Section II - Manual (Page 33)

AL Control (0x0120:0x0121)
Slave Controller – Register Description II-21
3.20 AL Control (0x0120:0x0121)
Table 24: Register AL Control (0x0120:0x0121)
ESC20 ET1100 ET1200 IP Core
[15:5]
(w ack) (w ack) (w ack)
[15:5]
V2.4.0/
V2.04a
Bit Description ECAT PDI Reset Value
3:0 Initiate State Transition of the Device State
Machine:
1:
Request Init State
3: Request Bootstrap State
2: Request Pre-Operational State
4: Request Safe-Operational State
8: Request Operational State
r/(w) r/
(w ack)* 1
4 Error Ind Ack:
0:
No Ack of Error Ind in AL status register
1: Ack of Error Ind in AL status register
r/(w) r/
(w ack)* 0
5 Device Identification:
0:
No request
1: Device Identification request
r/(w) r/
(w ack)* 0
15:6 Reserved, write 0 r/(w) r/
(w ack)* 0
NOTE: AL Control register behaves like a mailbox if Device Emulation is off (0x0140.8=0): The PDI has to
read/write* the AL Control register after ECAT has written it. Otherwise ECAT cannot write again to the AL Control
register. After Reset, AL Control register can be written by ECAT. (Regarding mailbox functionality, both registers
0x0120 and 0x0121 are equivalent, e.g. reading 0x0121 is sufficient to make this register writeable again.)
If Device Emulation is on, the AL Control register can always be written, its content is copied to the AL Status
register.
* PDI register function acknowledge by Write command is disabled: Reading AL Control from PDI clears AL Event
Request 0x0220[0]. Writing to this register from PDI is not possible.
PDI register function acknowledge by Write command is enabled: Writing AL Control from PDI clears AL Event
Request 0x0220[0]. Writing to this register from PDI is possible; write value is ignored (write 0).