behind the CAN ID and ends with byte 8. In a byte with value 1 bit 1 is set, in a byte with
value 128 bit 8 is set.
These enumeration scheme matches the one used in J1939 standard documents so that
you can directly copy the position. Engine coolant temperature is defined as the first byte -
so set start position to 1:1.
Alternatively one can type the bit position directly: 1 refers to the bit closest to the CAN
identifier and 64 is the bit at the end of the CAN message.
Warning: This input does not always behave as expected when typing position by hand.
Finally the displayed "byte:bit" value is relevant.
The mapping is filled correctly if there are no gaps i.e. the whole message gets filled with
values.
Please refer to the following image for byte and bit enumeration within a CAN message.
This enumeration is valid for little and big endian variables since it only refers to the CAN
message itself.
Length
Defines the size of the mapped numeric variable or constant in bits. If a string is mapped
this defines the length of the string in bytes.
Mapped length can be shorter than the length defined for the variable but not longer. By
default the variable length is used.
Is Constant
Enable this checkbox to define a constant. Depending on the mask constants can be used
to fill gaps or recognize multiplexers in receive mappings. In transmit mappings constants
are required for every part of the message not filled with a variable.
Uncheck this property to map a variable.
Constant Value
Although appearance does not change this property is only valid and editable for constants
i.e. lines where "Is Constant" property is set.
If valid this defines the numeric value of the constant. Please note that constants are always
expected to be numeric - there is no option to define string constants.
Group
Variable group containing the variable to be mapped. Does not apply to constants.
Variable
The variable to be mapped.
Mask
Variable or constant are bitwise ANDed with mask before they are applied.
See receive condition on how this can be used to receive multiplexed PGNs.
See section mapping calculations for details about how this property applies to receive
and transmit mappings.
Offset1
Offset 1 is a decimal value applied to the received value after mask and shift factor but
before scale and offset 2.
See section mapping calculations for details about how this property applies to receive
and transmit mappings.
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