TSS461C
37
Rev. D (22 Feb 01)
RM_L[4:0]:
Message length of the received frame.
If the DATA field of the received frame included DATA0 to
DATAn, RM_L[4:0] = n+1, even if the reserved length (Message Length
& Status Register) is larger.
Data Frame
Immediate
Reply
I, P
C
Frame Type
Node x
Message Status on Node A after IT(*)
Commu–
nication
Node A
RAK
RNW
RTR
length
previous
value
I, C
P
RAK
RNW
RTR
Deferred
Reply
previous
value
I, C
P
RAK
RNW
RTR
Data Frame
I, P
C
Immediate
Reply
I, C
P
RAK
RNW
RTR
length
Deferred
Reply
I, C
P
RAK
RNW
RTR
length
previous values
P: Producer
(*) After IT ROK or RNOK. In case of IT RE, the values can be erroneous.
I: Initiator
C: Consumer
Figure 24. Message Status updating
10.2. Message Data (string pointed by:
Message Pointer Register + 1
)
7
6
5
4
3
2
1
0
DATAn
-
-
-
-
-
-
-
-
DATA0
DATA0 is the first received (or transmitted) byte, DATAn is the last one.
Note 1: If the length reserved (in the message length & status register) for an incoming frame is 2 bytes greater or more,
the TSS461C will write the 2 bytes of the CRC field in the message string just after DATAn.
Because the VAN frame does not content a message length, the only way for the component to know the length of the
DATA field is either the message length register value, either the EOD field detection. When the reserved length is
too large, at the moment when it detects the EOD, the TSS461C has already written the 2 bytes of the CRC field,
considering these bytes as normal DATA.
Note 2: The Mailbox RAM area is a circular buffer. The next location after 0xFF is 0x80.