Echelon SLTA-10 - Presentation Layer Protocol

SLTA-10 Adapter User’s Guide 89
Presentation Layer Protocol
The network driver exchanges LonTalk packets with the host application at the presentation
layer. The LonTalk packet enclosed in a command of type
niCOMM
or
niNETMGMT
is described in
detail in the
Host Application Programmer's Guide
. It is summarized here for convenience.
ExpMsgHdr
or
NetVarHdr
SendAddrDtl
or
RcvAddrDtl
or
RespAddrDtl
UnprocessedNV
or
ExplicitMsg
Message
Header
size = 3
Network
Address
size = 11
Data
size
varies
Figure 36 Application Buffer Format
The SLTA-10 firmware is configured with explicit addressing enabled, and therefore the 11-byte
network address field is always present in an uplink or downlink buffer. The firmware is also
configured with host selection enabled, so the data field of the buffer is either an unprocessed
network variable or an explicit message.