Raw CAN Transmit Messages - Intrepidcs API
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To transmit a message you must assemble a transmit message as shown in tables 1 and 2 below. This is a transmit request. When neoVI has successfully transmitted a message it will send a transmit complete report. If you send messages faster than neoVI can place them on the bus you can cause a Main51 Transmit FIFO overflow to occur.

 

Table 1 - Transmit Standard Arbitration ID (SID) Frame Format

BYTE 1 BYTE 2 BYTE 3 BYTE 4 BYTE 5 BYTE 6

BYTES 7-14
 NETID_XX

NETID OF CAN NETWORK:

NETID_HSCAN, NETID_MSCAN, NETID_SWCAN, NETID_LSFTCAN

 DESCRIPTION ID MSB DESCRIPTION ID LSB STANDARD ARB
ID BITS 10:3
b7 b6 b5 b4

b3

 b2 b1 b0
SID Bit2 SID Bit1 SID Bit0

-

 IDE - EID Bit17 EID Bit16

IDE = Set to 0 when this is a standard frame.
EID Bit 17 and 16 = undefined  for a standard ID message

 
MS Nibble LS Nibble
b7 b6 b5 b4
- RTR - -
DLC
DLC = Data Length Code

RTR = Remote Transmit Request set to 1 for a remote frame (no data)

 

 CAN Data bytes 0 - 8

Remote Frame Have No Data

Table 2 - Extended Arbitration  ID (EID) Frame Format

BYTE 1 BYTE 2 BYTE 3 BYTE 4 BYTE 5 BYTE 6 BYTE 7 BYTE 8 BYTE 9-16
 NETID_XX

NETID OF CAN NETWORK:

NETID_HSCAN, NETID_MSCAN, NETID_SWCAN, NETID_LSFTCAN

 TIMESTAMP MSB TIMESTAMP LSB EXTENDED ARB
ID BITS 28:21

 

b7 b6 b5 b4

b3

 b2 b1 b0
EID Bit20 EID Bit19 EID Bit18

-

 IDE - EID Bit17 EID Bit16

IDE = Set to 1 when this is an extended frame.

 

 

 EXTENDED
ID BITS 15:8		 EXTENDED
ID BITS 7:0
MS Nibble LS Nibble
b7 b6 b5 b4
- RTR - -
DLC
DLC = Data Length Code

RTR = Remote Transmit Request set to 1 for a remote frame (no data)

 CAN Data bytes 0 - 8

Remote Frame Have No Data

 

 

 

C/C++ Examples:

    Changing the Arb ID into Bytes for a Standard Frame

bData[3] = uiArbID >> 3; // standard id high ( shift left 3 bits )

bData[4] = (uiArbID & 7) << 5; // mask off upper five bits

    

Changing the Arb ID into Bytes for an Extended Frame

// 4 header bytes with the standard ID first
bData[3] = uiArbID  >> 21; 
bData[4] = (((uiArbID  & 0x001C0000) >> 13) & 0xFF) + (((uiArbID   & 0x00030000) >> 16) & 0xFF) | 8; 
bData[5] = (uiArbID >> 8) & 0xFF; // extended id high
bData[6] = (uiArbID & 0xFF); // extended id id least significant bits

 

 

 

intrepidcs API   Documentation - (C) Copyright 2000-2012 Intrepid Control Systems, Inc.

Last Update: Tuesday, December 03, 2002