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Example for calculating the current temperature value:
Given value hexadecimal Given value decimal Subtract by
Actual temperature
0x49
73
40
33 °C
9.6.2
Current voltage
The object for storing the voltage is object number 201 (0xC9). The value is a 16 Bit
hexadecimal value LSB first in data bytes 3 and 4. The value needs to be transferred into
decimal and then shows the current voltage in mV.
Example for calculating the current Voltage:
Given value hex byte 3 Given value hex byte 4 Value ordered and in
decimal
Actual voltage
0xEB
0x34
13547 mV
13,547 V
9.6.3
Error handling
9.6.3.1 Active diagnostic trouble codes (DM1)
For the active diagnostic trouble codes two ways of communication are possible:
̶
Only one active diagnostic trouble code:
The DM1-message is send as shown:
The data field contains the trouble Code in data Byte [2-5]. The data Byte [0, 1, 6, 7] are not
used by the keypad and send as 0x00 [0, 1] or [6, 7]. A detailed structure of the Trouble Code
is shown below:
Bit TC1
TC2
TC3
TC4
0
SPN[0]
SPN[8]
FMI[0]
OC[0]
1
SPN[1]
SPN[9]
FMI[1]
OC[1]
2
SPN[2]
SPN[10]
FMI[2]
OC[2]
3
SPN[3]
SPN[11]
FMI[3]
OC[3]
4
SPN[4]
SPN[12]
FMI[4]
OC[4]
5
SPN[5]
SPN[13]
SPN[16]
OC[5]
6
SPN[6]
SPN[14]
SPN[17]
OC[6]
7
SPN[7]
SPN[15]
SPN[18]
0
TC1 contains the Low Byte of the SPN and TC2 the second Byte. The Bit 16, 17 and 18 of the
SPN are Bit 5, 6 and 7 of TC3. The SPN values of all possible errors are shown in the J1939
K-matrix for the rugged keypad. TC3 Bit 0-4 contains the Failure Mode Identification Code
(FMI). The 32 possible FMI codes are described in SAE J1939-73. TC4 contains the
occurrence count of the active error. The maximum value of occurrence count is 127. Bit 7 of
TC4 contains the SPN conversion method and is set to 0.
CAN-ID
DLC Data
Byte 0
Data
Byte 1
Data
Byte 2
Data
Byte 3
Data
Byte 4
Data
Byte 5
Data
Byte 6
Data
Byte 7
0x18FECA80 8
0x00
0x00
TC1
TC2
TC3
TC4
0xFF
0xFF
