DynaGen Tough TG350AMF, User Manual

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Configuration 47
© 2012 DynaGen Technologies Inc. TOUGH Series User Manual
4.7.4 DTC Conversion Methods
This section is used to decode the information contained in the Modbus DTC (DM1 and DM2) registers if
the ECM does not support the newest DTC conversion method. The DTC's for J1939 are specified in a
specific format. Older J1939 specifications had three conversion methods and is impossible to tell them
apart without contacting the engine manufacturer.
Newer J1939 specifications follow SPN method (Version 4) and can be determined by looking at the CM
bit. It will be set to 1 for Version 4 and set to 0 for Versions 1, 2, and 3. If the CM bit is 0, use
conversion methods listed below. Byte 1 to Byte 4 refers to the individual bytes in the controllers DTC
Modbus registers..
DTC Conversion Method (Version) 1
BYTE CONVERSION
Byte 1 8 most significant bits of 16 most significant bits of SPN
Byte 2 8 least significant bits of 16 most significant bits of SPN
Byte 3
3 most significant bits of byte contain the 3 least significant bits of SPN 5 least
significant bits of byte contain the FMI
Byte 4 Most significant bit of byte contains CM 7 least significant bits of byte contains OC
DTC Conversion Method (Version) 2
BYTE CONVERSION
Byte 1 8 least significant bits of 16 most significant bits of SPN
Byte 2 8 most significant bits of 16 most significant bits of SPN
Byte 3
3 most significant bits of byte contain the 3 least significant bits of SPN 5 least
significant bits of byte contain the FMI
Byte 4 Most significant bit of byte contains CM 7 least significant bits of byte contains OC
DTC Conversion Method (Version) 3
BYTE CONVERSION
Byte 1 8 least significant bits of SPN
Byte 2 8 second byte of SPN
Byte 3
3 most significant bits of byte contain the 3 most significant bits of SPN 5 least
significant bits of byte contain the FMI
Byte 4 Most significant bit of byte contains CM 7 least significant bits of byte contains OC
DTC conversion method 3 is the same as DTC conversion Method 4 except that the CM bit is 1 so it is
impossible to tell it apart from versions 1 and 2. Version 4 has the bit set to 0 which allows the user to
know the conversion format without consulting the engine manufacturer.