WAGO 750-632 Manual page 112

112 Appendix
received status nibble is receipt 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 image.
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 control now has to confirm receipt of this fragment. Receipt is confirmed by
inverting the toggle bit of the status nibble to be sent.
Because the Mailbox 2.0 mechanism is full-duplex capable, data can be sent and
received at the same time..
Manual
Version 1.3.1, valid from FW/HW-Version 01/01
WAGO I/O System 750/753
750-632 Proportional Valve Module