National Instruments CAN 372139B-01 - Manual (Page 177)

Chapter 6 Automotive Diagnostic Command Set API for C
© National Instruments Corporation 6-13 Automotive Diagnostic Command Set User Manual
ndConvertFromPhys
Purpose
Converts a physical data value into a binary representation using a type descriptor.
Format
void ndConvertFromPhys(
TD2 *typeDescriptor,
double value,
unsigned char dataOut[],
long *len);
Input
typeDescriptor
A struct that specifies the conversion of the physical value to its binary representation:
typedef struct {
long StartByte;
long ByteLength;
unsigned short ByteOrder;
unsigned short DataType;
double ScaleFactor;
double ScaleOffset;
} TD2;
StartByte is ignored by ndConvertFromPhys .
ByteLength is the number of bytes in the binary representation.
ByteOrder defines the byte order for multibyte representations. The values are:
0: MSB_FIRST (Motorola)
1: LSB_FIRST (Intel)
DataType is the binary representation format:
0: Unsigned. Only byte lengths of 1–4 are allowed.
1: Signed. Only byte lengths of 1–4 are allowed.
2: Float. Only byte lengths 4 or 8 are allowed.
ScaleFactor defines the physical value scaling:
Phys = ( ScaleFactor ) * (binary representation) + ( ScaleOffset )
ScaleOffset (refer to ScaleFactor )
value
The physical value to be converted to a binary representation.