Rockwell Automation 1756-RIO ControlLogix Remote I/O Communication Interface Module User Manual - Manual (Page 131)

Publication 1756-UM534B-EN-P - November 2010 131
Scanner Mode I/O Map Appendix A
Discrete Output Data
In scanner mode, the discrete write structure for a rack consists of two control
words and eight words of discrete output data.
Discrete Write Structure-Output
Bits 0…3 of the first word of control data are used to inhibit racks. Set bit 0 to
inhibit the scan of the rack starting at I/O group 0; set bit 1 to inhibit the scan
of the rack starting at I/O group 2; and so on. Inhibiting a rack stops all
communication with that rack and all outputs revert to their programmed last
state.
Bits 4…7 of the first word of control data are used to reset racks. Set bit 4 to
reset the outputs of the rack starting at I/O group 0; set bit 5 to reset the
outputs of the rack starting at I/O group 2; and so on. When a reset command
is given, all communication with that rack continues; however, that rack
behaves as if the controller is in Program mode. All outputs revert to their
Program mode state.
Only the bit for the starting I/O group needs to be set to inhibit or reset the
rack. For example, if a rack is a full rack starting at I/O group 0, only bit 0
needs to be set to inhibit the scan of the rack.
Words 2…9 contain the discrete output data for the rack. Words 2 and 3
contain the data for I/O groups 0 and 1 (first 1/4 rack), words 3 and 4 contain
the data for I/O groups 2 and 3 (second 1/4 rack), and so on.
0 1 2 3 4 5 6 7 8 9
2 Control Words Discrete Output Data
1st
16-bit
Word
44818