NIM Primitives
4-3
TIWAY 1 Ti505 NIM User Manual
Figure 1 illustrates the basic Primitive structure when HDLC operation is selected.
There is a Request Format and a Response Format, as shown. The binary weight of the
fields is detailed in Figure 2. All field lengths are multiples of 8 bits, which allows for
octet testing of data link frames at the data link/media access control layer.
HDLC I Frame or UI Frame
Flag
Address Control Information
FCS
Flag
Bit
0
8
16
24
N – 24
N – 8
N
Length
Primitive Code
Descriptor(s) Data Unit(s)
Primitive Fields
Request Format
Response Format
MSB
LSB
Length
Prim / Error Secondary StatusData Unit(s)
Figure 1 Basic Primitive Structure
The maximum length of the Information field is 273 bytes for the Series 505
NIM. In the
Request, the 273 bytes include the Length, Primitive code, Descriptor, and Data Unit
fields. In the Response, the 273 bytes include the Length, Primitive Code/Error, Secon-
dary Status, and Data Unit fields. In both formats, the 273 bytes exclude the protocol
control fields. The actual length supported is dependent on the attached device type and
must be ascertained with the Format Configuration Primitive 04.
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