Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 73)

Chapter
5
Publication 1770Ć6.5.16 - October 1996
DataĆlink Layer Message
Frames
In the data-link layer of a message frame:
•
half-duplex protocol uses three types of message transmission
•
full-duplex protocol implements its message fields at different
network layers
•
at the end of each polling and message frame, there is a one-byte
BCC field or a two-byte CRC field
Read this chapter to help learn the fields that your computer uses in
the data-link layer of a message frame. It contains these sections:
Section Page
HalfĆduplex Protocol Message Frames 5-2
FullĆduplex Protocol Message Frames 5-3
BCC and CRC Fields 5-4