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CHAPTER 19 FCAN CONTROLLER (V850/SC3)
User’s Manual U15109EJ3V0UD
648
19.10.5 Overload frame
An overload frame is transmitted under the following conditions.
•
When the receiving node is not yet ready to receive.
•
If a dominant level is detected at the first two bits during intermission mode.
•
If a dominant level is detected at the last bit (8th bit) of the end of frame or at the last bit (8th bit) of the error
delimiter/overload delimiter.
Figure 19-24. Overload Frame
<1>
R
D
<2>
<3>
6 bits
0 to 6 bits
8 bits
(<4>)
(<5>)
Interframe space or overload frame
Overload delimiter
Overload flag (node n)
Overload flag (node m)
Frame
Overload frame
Remarks 1.
Node n/node m: Each node (n
≠
m)
2.
D: Dominant = 0
R: Recessive = 1
Table 19-23. Field Definition of Overload Frame
No
Name
Bit count
Definition
<1>
Overload flag starting from
node m
6
Consecutive output of 6 dominant-level bits.
Output when node m is not ready to receive.
<2>
Overload flag starting from
node n
0 to 6
Node n, which has received an overload flag in the interframe
space, outputs an overload flag
<3>
Overload delimiter
8
Consecutive output of 8 recessive-level bits.
If a dominant level is detected at the eighth bit, an overload
frame is sent starting at the next bit.
<4>
Frame
–
Output following an end of frame, error delimiter, or overload
delimiter.
<5>
Interframe space or overload
frame
–
An interframe space or overload frame starts from here.
Remark
Node n/node m: Each node (n
≠
m)