User's Manual

Table Of Contents
The length of the header is one word and should appear at the beginning of
each incoming and outgoing message. When you setup your message sizes
you will have 2 bytes overhead. In essence, for a 28 byte message, you will
have 2 bytes of non-data overhead in each DeviceNet message. The
DeviceNet message will be fragmented into four, 8 byte fragments. The first
byte of every fragment is reserved for the fragment header byte. The frag
-
ment header byte count is not included in the total message size.
A configuration option called ABx separation, instructs the LRP830 to
place only one ABx command message response in each DeviceNet mes
-
sage. The default is set to ABx_sep = on.
Examples
When the PLC has data available to send to the LRP830, it sets the “REQ”
bit in the DeviceNet message header. If the message length is 30 bytes, then
the message is fragmented and structured as follows from the PLC. The
header byte is underlined and italicized.
Note:
The fragmentation byte appears in every fragment, but the header word
appears only in the first fragment. The SENSOR bit (0) may be consistently
on but should be ignored.
Copyright © 2000 Escort Memory Systems
180 LRP830-Series Long-Range Passive Reader/Writer