Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 32)

Configuring the Scanner through LIST
Chapter 2
2-6
ATTENTION: Selecting reconfiguration while the controller is
in the run mode and executing block transfers could cause a bad
address fault.
If this situation occurs, you should:
Clear the bad address fault in a fault routine.
Clear the block transfer error bit.
Restart the block transfer in the ladder program
I/O Scan Configuration
When you configure an I/O channel for I/O scan, you can change the order
and priority that the scanner scans the I/O chassis. You do this by listing
the I/O chassis in the order that you want the scanner to communicate with
them. This allows you to assign a higher priority to some I/O chassis than
to others by listing the higher priority chassis more than once.
For example, suppose your I/O chassis scanning sequence list has six
entries, and entries 1 and 4 are the same. Then the scanner updates the
chassis listed as entries 1 and 4 twice as often as the other chassis.
Each I/O chassis is listed once in the default configuration at initial
power-up or after auto configure. You can alter the list to repeat a chassis
as often as desired, provided that the list contains no more than 32 entries.
An asterisk (*) appearing before an entry in the list indicates that the
corresponding I/O chassis or adapter is faulted.
To enter a chassis into the I/O chassis scanning sequence, use the format
shown in Figure 2.2.
Figure 2.2
Entering a Chassis into the I/O Chassis Scanning Sequence List
entry / rack / size / I/O group / attributes
Position of entry in the
scanning sequence list
Assigned I/O rack
number (0 Ć 376
8
)
Number of I/O groups in
the chassis (2, 4, 6, or 8)
Starting I/O group
number in the chassis (0, 2, 4, or 6)
I or F
I = Chassis is for inputs only
F = Major fault is declared if chassis faults
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