Rockwell Automation 2706-LV2P_LV2R_LV4P_LV4R DL40 PLUS USER MANUAL - Manual (Page 127)

Remote I/O Communications 8–35
Publication 2706-6.1
Bit Trigger Table
The Bit Trigger Table has 2 sections, the Priority section and the
Round Robin section.
With 1 /
4
rack, Bit Trigger Table must be either priority section or
round robin section. The length (in words) of the Priority Section is
set in the Offline Programming Software. The length of the Round
Robin Section is what is left over (total table length minus the
Priority Section length minus 1). With Discrete I/O, the length of the
table is 1, 3, 5, or 7 words long depending on rack configuration (
1 /
4
,
1 /
2
, 3 /
4
, full). With 16 bits per word, the maximum number of
messages that can be triggered with discrete I/O is 112 (total for
priority and/or round robin messages). The total length of the Bit
Trigger Table for Block Transfer is 32 words. With 16 bits per word,
the maximum number of messages that can be triggered is 496. Both
sections are in whole words. In addition, Priority Message Numbers
can be sent.
Triggering Messages Using Discrete I/O
The following shows the format of discrete I/O bit triggering.
WORD 1
17 16 15 14 WORD 0
Output Image Table
WORD 2
WORD 3
WORD 4
WORD 5
WORD 6
Priority Message Number
Handshake Bit
Full rack
1/2 rack
3/4 rack
WORD 7
Msg. 16
Msg. 32
Msg. 48
Msg. 64
Msg. 80
Msg. 96
Msg. 112
Msg. 1
Msg. 17
Msg. 33
Msg. 49
Msg. 65
Msg. 81
Msg. 97
Bit Trigger Table
Bit Trigger Table
Bit Trigger Table
Bit Trigger Table
Bit Trigger Table
Bit Trigger Table
Bit Trigger Table