NIM Primitives
4-9
TIWAY 1 Ti505 NIM User Manual
4.5.1
Field Symbols
The symbols used in the remainder of this section to denote the different types of Primi-
tive fields are summarized in Table 3.
The length of the field (in bytes) is represented by the number of characters in the field
symbol. A byte is represented by two symbols. For example, the field LLLL is a two-byte
(16 bit) field. Field symbols with “. . .” are variable length fields.
Table 3 Summary of Primitive Field Symbols
Symbol
Description
LLLL
Length field
PP
Primitive code
HH
Attached device status
TT
Data element types
NNNN
Number of data elements
AAAA or AAAA AAAA
Data element location
DDDD
Data unit(s)
XX
Number of user–defined structures
requested
CC
User–defined structure number
4.5.2
Length Field – LLLL
The Length Field is a 16-bit field that represents the length (in bytes) of the Primitive,
Descriptor(s), and Data Unit field(s). The Length Field is initialized by the Primary in
transmissions to the NIM. It is also initialized by the NIM in transmissions to the Prima-
ry. (Example: the Length Field for a Primitive 02 request would have a value of 1.)
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