User`s guide

Aironet Wireless Communications, Inc. 8-3 Confidential and Proprietary
Frame Type
Length
Parameter #1
Parameter #2
•
•
•
Data
Checksum
Closing byte
Figure 8.1 - PLAP Packet Format
The PLAP frame consists of the following fields.
• The first field is Frame Type which identifies the type of frame. Several types are
defined and described in the next sections. The Most Significant Bit (MSB) is used
to indicate if the checksum field is operational (see checksum field description
below).
MSB = 0; checksum field is valid
MSB = 1; checksum field is not valid
• Following Frame Type is the two-byte Length field. The Length field contains the
total length of the frame from the Frame Type character to the Closing character
inclusive. The length is sent high byte first.
• Following the Length field are the set of parameters, if any, that each frame type
requires. The number of parameters can be different for each type. Any data
associated with the frame type immediately follows the last parameter. This can be
of any length from 0 to 1514 characters.
• Following the data is a two-byte checksum which is the inclusive addition of all
characters in the frame excluding the checksum and closing byte. Note: MSB of
frame type must be 0 if this field is valid.
• The closing character is simply a defined character used as another verification that
framing was maintained in the packet. The character used is the ASCII EOT
character 0x04.
Note: all word or long word fields are sent big endian (Motorola format) MSB to LSB with the high byte
sent first. Character data is treated as a byte stream.