Welch Allyn SureTemp PlusModule - User Manual - Manual (Page 55)

SureTemp Plus Module OEM Implementation Communications Protocol
Welch Allyn OEM Technologies Confidential 55
Command and Response Strings: Examples
This section provides examples of command and response strings for some of the more
commonly used commands. It also provides a brief description, with examples, of endianness.
Endianness
Big-Endian Numbers
In big-endian machines—typical of Motorola® processors—the high-order byte is first:
Command Code (Word): 0x94 0x1C = 0x941C
Little-Endian Numbers
In little-endian machines—typical of Intel® processors—the low-order byte is first:
Byte Count (Word): 0x13 0x00 = 0x0013.
In IEEE 754 little-endian floating-point numbers, the least-significant byte is first:
IEEE 754 Data Format
The IEEE 754 floating-point data format consists of four contiguous bytes: a 23-bit signed binary
mantissa and an 8-bit biased binary exponent:
Converting a String of Bytes to a Floating-Point Number
1. Swap the bytes to the endian format used by processor on which the software is running.
2. In C, cast the number to a float
Decimal Hexadecimal
100.0 00 00 C8 42
-100.0 00 00 C8 C2
0.5 00 00 00 3F
-1.75 00 00 E0 BF
0.56 29 5C 0F 3F
0.0625 00 00 80 3D
Bits Description
0 Sign of the mantissa (0 = positive; 1 = negative)
1 - 8 Exponent (8-bit unsigned value)
(The implied binary point is between bits 8 and 9.)
9 - 31 Mantissa