Mantracourt Electronics Limited
DCell & DSC MantraCAN User Manual
50
CAN ID
CAN Data
ID + 1
Descriptor
Command Number
11 or 29 bit
NAK
1 Byte
The reason for a NAK response would be if the command number does not exist in the device.
Example of Read
The following example is to read SYS from an ID of 100.
Message from Master
CAN ID
CAN Data
Base ID
Descriptor
Command Number
0x64
0x1
0xA
Hexadecimal
100
1
10
Decimal
Successful Response From Slave. The value returned is 123.456
CAN ID
CAN Data
Base ID + 1
Descriptor
Command Number
Data
0x65
0x6
0xA
0x3F, 0x80, 0x00, x00
Hexadecimal
101
6
10
63, 128, 0, 0
Decimal
Not Acknowledged Response From Slave. For example if the device did not support command number 10
CAN ID
CAN Data
Base ID + 1
Descriptor
Command Number
0x65
0x15
0xA
Hexadecimal
101
21
10
Decimal
Write
To
write a parameter
send message to appropriate ID with a Write descriptor and IEEE floating point data.
Message From Master
CAN ID
CAN Data
Base ID
Descriptor
Command Index
Data
11 or 29 bit
Write
1 Byte
4 Bytes
Then wait a timeout period for a message of the same ID marked as either Response or NAK descriptor. If a response descriptor is returned then
this acknowledges receipt but does not contain data.
Successful Response From Slave.
CAN ID
CAN Data
Base ID + 1
Descriptor
Command Index
11 or 29 bit
Response
1 Byte
Not Acknowledged Response From Slave.
CAN ID
CAN Data
Base ID + 1
Descriptor
Command Index
11 or 29 bit
NAK
1 Byte