Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers User Manual
Page 53
Publication 1785-UM012D-EN-P - July 2005
Addressing I/O and Controller Memory 4-9
TIP
When assigning remote I/O rack numbers, use these
guidelines:
•
A single remote I/O scanner channel can support up to 32 devices
but only 16 rack numbers. For more information, see chapter 6.
•
Limit the number of remote I/O rack numbers to those that your
PLC-5 controller can support.
•
The PLC-5 controller and the 1771-ASB adapter module
automatically allocate the next higher rack number(s) to the
remaining I/O groups of the chassis. For example, if you select
1/2-slot addressing for your controller-resident local chassis and
you are using a 16-slot (1771-A4B) chassis, the controller will
address racks 0, 1, 2, and 3 in this chassis.
•
You can assign a remote I/O rack to a fraction of a chassis, a
single I/O chassis, or multiple I/O chassis as shown below.
01 23 45 67 01 23 45 67
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
16466
One 16-slot chassis, two racks
I/O Rack No. 0
One 16-slot chassis, one rack
One 8-slot chassis, 1/2 rack
Two 4-slot chassis, 1/4 rack each
I/O Rack No. 1
I/O Rack No. 3