National CP3BT26 - Manual (Page 132)

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CP3BT26
19.10.5 Storage of Remote Messages
During remote frame transfer, the buffer registers DATA0–
DATA3 are “don’t cares”. If a remote frame is transmitted,
the contents of these registers are ignored. If a remote
frame is received, the contents of these registers will be
overwritten with invalid data. The structure of a message
buffer set up for a remote frame with extended identifier is
shown in Table 56.
SRR The Substitute Remote Request bit replaces
the RTR bit used in standard frames at this bit
position. The SRR bit needs to be set by soft-
ware.
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 to build the 29-bit identifier
of an extended frame. The ID[28:18] field is
used for the 11 standard frame identifier bits.
Table 56 Extended Remote Frame
Address
Buffer
Register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0E F0XEh ID1 ID[28:18] SRR IDE ID17:15]
0E F0XCh ID0 ID[14:0] RTR
0E F0XAh DATA0
Don’t Care
0E F0X8h DATA1
0E F0X6h DATA2
0E F0X4h DATA3
0E F0X2h TSTP TSTP
0E F0X0h CNSTAT DLC Reserved PRI ST