National CP3BT26 - Manual (Page 130)

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CP3BT26
PRI The Transmit Priority Code field holds the
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.
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.
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.
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
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.
ID The ID field is used for the 11 standard frame
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