76 Appendix
WAGO-I/O-SYSTEM
750
750-657 IO-Link Master
Manual
Version 1.0.2, valid from FW/HW-Version 02/01
Structure of the simple header:
Table 34: Structure of the simple header
Simple header
Bit 7 Bit 6
Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0
Length
Structure of the extended header:
Table 35: Structure of the extended header
Extended header
Bit 7 Bit 6
Bit 5..0
Bit 7..0
Bit 7..0
1
0
Length High
Length Low
Protocol ID
A message that uses this header can contain 16383 bytes of user data. In addition,
the message can have a protocol ID. This protocol ID allows the message to
include a logical meaning.
11.1.1.2 Transmission channel
To transfer a message over a narrow channel, synchronization between sender and
receiver is required. Therefore, the transmission channel is divided into a
synchronization part and a data part.
For synchronization, a so-called handshake byte (HB) is defined.
The handshake byte occupies the first byte of the transmission channel while part
of the message is always delivered in the remaining bytes.
There is always one transmission channel from the sender to the receiver and one
transmission channel from the receiver to the sender. Both channels do not have to
be the same size. However, the minimum size is 1 byte.
Data element length max. 127 bytes
0: Simple header
Protocol ID 0..255
Data element length
max. 16383 bytes
10: Extended header
HB
Part of the message
