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38 EuroPak-15a Receiver User Manual Rev 5
Chapter 4 Using Commands and Logs
4.4 Fields
The commands and logs for the EuroPak-15a use a variety of field types to convey data. The following sections
provide information on the types of fields used and some of the more commonly-used fields.
4.4.1 Field Types
The following table describes the field types used in the commands and logs.
Table 8: Field Types
Section 9 on Page 39 shows the arrangement of bytes within each field type when used by IBM PC computers.
All data sent to or from the receiver, however, is read Least Significant Bit (LSB) first, opposite to what is
shown in Table 9. Data is then stored in the receiver LSB first. For example, in char type data, the LSB is bit 0
and the Most Significant Bit (MSB) is bit 7.
Type
Binary Size
(Bytes)
Description
Char 1
An 8-bit signed integer in the range -128 to +127. This integer value may
be the ASCII code corresponding to the specified character. In ASCII or
Abbreviated ASCII this comes out as an actual character.
UChar 1
An 8-bit unsigned integer. Values are in the range from +0 to +255. In
ASCII or Abbreviated ASCII this comes out as a number.
Short 2 A 16-bit signed integer in the range -32768 to +32767.
UShort 2 A 16-bit unsigned integer in the range +0 to +65535.
Long 4 A 32-bit signed integer in the range -2147483648 to +2147483647.
ULong 4 A 32-bit unsigned integer in the range +0 to +4294967295.
Double 8
64 bits, with 1 for the sign, 11 for the exponent, and 52 for the mantissa.
Its range is ±1.7E308 with at least 15 digits of precision. This is IEEE
754.
Float 4
32 bits, with 1 for the sign, 8 for the exponent, and 23 for the mantissa.
Its range is ±3.4E38 with at least 7 digits of precision. This is IEEE 754.
Enum 4
A 4-byte enumerated type beginning at zero (an unsigned long). In
Binary, the enumerated value is output. In ASCII or Abbreviated ASCII,
the enumeration label is spelled out.
GPSec 4
Two separate formats that depend on whether the output is requested in
Binary or an ASCII format. For Binary the output is in milliseconds and
is a long type. For ASCII the output is in seconds and is a float type.
Hex n
A packed, fixed length (n) array of bytes in Binary but in ASCII or
Abbreviated ASCII is converted into 2 character hexadecimal pairs.
String n
A variable length array of bytes that is null-terminated in the Binary case.
The maximum byte length for the field is shown in the row in the log or
command table.