WAGO 750 Product Manual page 81

750-1632/000-100
8.2.5 Data Exchange
In the data exchange phase, the handshake byte is used in Toggle mode. Because a
message is normally larger than the data part of the transmission channel, the message
must be transferred in several cycles (fragmentation).
Bit 3
1
Send Fragment
The first toggle bit expected by the receiver after synchronization has the value 0. The
toggle bit in the second fragment receives a 1, the toggle bit in the third fragment again a
0, etc. Only when the status of the toggle bit matches in the received status nibble is re-
ceipt of the fragment confirmed by the receiver. Only then can a new fragment be sent.
As long as there is no confirmation, the fragment remains unchanged in the process im-
age. For the special case that the content of the send buffer is no longer sufficient to fill
the transmission channel completely, the transmission channel is filled with zeros to the
end.
Receive Fragment
The controller now has to confirm receipt of this fragment. Receipt is confirmed by invert-
ing the toggle bit of the Nibble status to be sent. Since the Mailbox 2.0 mechanism is full-
duplex, sending and receiving can be simultaneous.
The following example shows use of the transmission channel during a send operation
(no full-duplex transmission):
Product manual | Version: 1.1.0
Proportional Valve Module 2-3-4
Status Nibble
Bit 2 Bit 1 Bit 0
T 0x00
Control Nibble
Bit 3 Bit 2 Bit 1
1 T
Appendix
Bit 0
0x00
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