Transmission Channel; The Handshake Byte; Figure 57: Extended Header (Structure) - WAGO 750-632 Manual

WAGO I/O System 750/753
750-632 Proportional Valve Module
Structure of the extended header:

Figure 57: Extended Header (Structure)

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.
11.1.2

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.
11.1.2.1

The Handshake Byte

In general, a distinction is made between Control(C) and Toggle(T) mode (bit 7).
The Control mode is used to synchronize the subscribers. The Toggle mode is
used to exchange data.
Structure of the handshake byte:
Version 1.3.1, valid from FW/HW-Version 01/01
Appendix 107
Manual