X90 mobile modules
X90 mobile system User's manual V 1.20 - Translation of the original manual
217
MultiSegmentMTUs allowed
With this option, InputMTU is completely filled (if enough data is pending). The previously unfilled Rx bytes transfer
the next control bytes and their segments. This allows the enabled Rx bytes to be used more efficiently.
Bus cycle 1
Control byte with MessageEndBit = 0
Bus cycle 2
Bus cycle 3
-
-
ME1
C
ME1
C
ME0
C
ME1
C
Control byte with MessageEndBit = 1
Segment 1
Segment 2
Segment 4
Message 1
Message 2
ME0
C
ME0
C
3
Figure 52: Arrangement of messages in the MTU (MultiSegmentMTUs)
Large segments allowed:
When transferring very long messages or when enabling only very few Rx bytes, then a great many segments must
be created by default. The bus system is more stressed than necessary since an additional control byte must be
created and transferred for each segment. With option "Large segments", the segment length is limited to 63 bytes
independently of InputMTU. One segment is permitted to stretch across several sequences, i.e. it is possible for
"pure" sequences to occur without a control byte.
Information:
It is still possible to split up a message into several segments, however. If this option is used and
messages with more than 63 bytes occur, for example, then messages can still be split up among
several segments.
Bus cycle 1
Control byte with MessageEndBit = 0
Bus cycle 2
Bus cycle 3
-
-
-
ME1
C
ME1
C
ME0
C
ME1
C
Control byte with MessageEndBit = 1
Segment 1
Segment 2
Segment 3
Message 1
Message 2
-
Figure 53: Arrangement of messages in the MTU (large segments)