78 Appendix
WAGO-I/O-SYSTEM
750
750-657 IO-Link Master
Manual
Version 1.0.2, valid from FW/HW-Version 02/01
11.1.1.3 Communication Phases
The Mailbox 2.0 mechanism defines two communication phases:
• Synchronization
• Data
exchange
Only after successful synchronization from sender to receiver can the actual user
data be exchanged.
11.1.1.3.1 Synchronization
In the synchronization phase, the handshake byte is used in Control mode.
A distinction is made between interpretation as signaling mode and interpretation
as command acknowledgement mode.
In command acknowledgement mode, the handshake byte appears as follows:
Status nibble
Control nibble
Bit 3 Bit 2
Bit 1
Bit 0
Bit 3
Bit 2 Bit 1
Bit 0
0
Acknowledgement 0
Acknowledgement
The Control nibble is used to transfer a request while the Status nibble contains
the response to the request.
11.1.1.3.1.1 Mailbox Commands
The following commands are defined:
Table 37: Commands
Value Meaning
Description
0
INVALID
Signals that the control has not started operations again after
a reset.
1
HOLD REQUEST
Notice that the channel is ready, but data is not currently
being transferred
(e.g. because the send buffer is still empty)
2
RESET REQUEST
Prompt to reset
3..7
-
(not supported, ignore)
