National CP3BT26 User Manual
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130
CP3BT26
PRI
The Transmit Priority Code field holds the
software-defined transmit priority code for the
message buffer.
software-defined transmit priority code for the
message buffer.
DLC
The Data Length Code field determines the
number of data bytes within a received/trans-
mitted frame. For transmission, these bits
need to be set according to the number of
data bytes to be transmitted. For reception,
these bits indicate the number of valid re-
ceived data bytes available in the message
buffer. Table 53 shows the possible bit combi-
nations for DLC3:0 for data lengths from 0 to
8 bytes.
number of data bytes within a received/trans-
mitted frame. For transmission, these bits
need to be set according to the number of
data bytes to be transmitted. For reception,
these bits indicate the number of valid re-
ceived data bytes available in the message
buffer. Table 53 shows the possible bit combi-
nations for DLC3:0 for data lengths from 0 to
8 bytes.
Note: The maximum number of data bytes received/trans-
mitted is 8, even if the DLC field is set to a value greater than
8. Therefore, if the data length code is greater or equal to
eight bytes, the DLC field is ignored.
mitted is 8, even if the DLC field is set to a value greater than
8. Therefore, if the data length code is greater or equal to
eight bytes, the DLC field is ignored.
19.10.2 Storage of Standard Messages
During the processing of standard frames, the Extended-
Identifier (IDE) bit is clear. The ID1[3:0] and ID0[15:0] bits
are “don’t care” bits. A standard frame with eight data bytes
is shown in Table 54.
Identifier (IDE) bit is clear. The ID1[3:0] and ID0[15:0] bits
are “don’t care” bits. A standard frame with eight data bytes
is shown in Table 54.
IDE
The Identifier Extension bit determines wheth-
er the message is a standard frame or an ex-
tended frame.
0 – Message is a standard frame using 11
er the message is a standard frame or an ex-
tended frame.
0 – Message is a standard frame using 11
identifier bits.
1 – Message is an extended frame.
RTR
The Remote Transmission Request bit indi-
cates whether the message is a data frame or
a remote frame.
0 – Message is a data frame.
1 – Message is a remote frame.
cates whether the message is a data frame or
a remote frame.
0 – Message is a data frame.
1 – Message is a remote frame.
ID
The ID field is used for the 11 standard frame
identifier bits.
identifier bits.
Table 53
Data Length Coding
DLC
Number of Data Bytes
0000
0
0001
1
0010
2
0011
3
0100
4
0101
5
0110
6
0111
7
1000
8
Table 54
Standard Frame with 8 Data Bytes
Address
Buffer
Register
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0E F0XEh
ID1
ID[10:0]
RTR IDE
Don’t Care
0E F0XCh
ID0
Don’t Care
0E F0XAh
DATA0
Data1[7:0]
Data2[7:0]
0E F0X8h
DATA1
Data3[7:0]
Data4[7:0]
0E F0X6h
DATA2
Data5[7:0]
Data6[7:0]
0E F0X4h
DATA3
Data7[7:0]
Data8[7:0]
0E F0X2h
TSTP
TSTP[15:0]
0E F0X0h
CNSTAT
DLC
Reserved
PRI
ST