Rockwell Automation 1775-S4B,D17756.5.3 User Manual SCANNER/MSG HND - Manual (Page 36)

Operating the LIST Function
Chapter 4
4Ć14
The 1775-S4B scanner removes the third entry in the rack list and
redisplays the rack list.
An asterisk (*) appearing before an entry in the rack list indicates that the
corresponding I/O chassis or I/O adapter module is faulted.
The I/O rack group selection in LIST selects the range of I/O rack numbers
that the I/O scanner module can address. Presently, the PLC-3 controller
uses only rack number 0 to 76
8
, and the first rack group is selected by
default, so you do not have to make a selection here.
The subscript (
8
) indicates that the value is expressed in an octal format.
If you plan to use rack numbers greater than 37
8
, consider the following:
Racks numbered greater than 37
8
increase the I/O scan time.
The amount of memory required for the input and output sections
depends on the highest rack number containing inputs or outputs,
respectively. Therefore, skipping rack numbers is an inefficient use of
memory.
The I/O channel portion of LIST includes selections for reconfig and auto
config. A reconfig implements other changes which you made in LIST. For
example, if you list an I/O chassis three times in the rack list, and you
change the rack list to include that chassis 6 times, the 1775-S4B scanner
does not change its polling sequence until you select reconfig. Reconfig
works for the all the I/O communication channels. Therefore, you can
reconfigure the I/O communication channels once, after making all I/O
channel selections, instead of making separate reconfigure selections for
each I/O channel.
If an asterisk is displayed next to the reconfig selection, change(s) have
been requested but not implemented. Upon selecting reconfig, the
1775-S4B scanner implements the changes and removes the asterisk.
CAUTION: If the PLC-3 processor is in the run mode and
executing block transfers, selecting reconfig could cause a bad
address fault to occur.
4.3.2
I/O Rack Group Selection
4.3.3
Reconfig and Auto Config