Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 600)

Section 10B
9/Series Adapter Modules for
1771 and 1746 I/O Devices
10B-11
The following section describes how to calculate how many ASRN chips
are used by either the 1771 or 1746 I/O devices. Refer to page 10A-2 for
information on the number of ASRN chips used by other 9/Series I/O ring
devices.
ASRN Chip Used by 1771 and 1746 I/O Chassis
The number of ASRN chips used by a 1746 or 1771 I/O chassis will vary
depending on the chassis size and the number and type of I/O cards
installed in the chassis. Different size chassis have a minimum number of
ASRN chips required (regardless of the number of I/O points) and different
I/O devices in the chassis require different numbers of ASRN.
To determine the number of ASRN “chips” used by the I/O chassis in a
specific I/O ring application, use the following procedure:
1. Determine “A”, the minimum chassis ASRN requirements:
1746 I/O Chassis 1771 I/O Chassis
Chassis Size: Minimum number
of ASRN chips:
Chassis Size: Minimum number
of ASRN chips:
4 slot (1746-B4) A = 3 4 slot A = 3
7 slot (1746-B7) A = 4 8 slot A = 5
10 slot (1746-B10) A = 6 12 slot A = 7
13 slot (1746-B13) A = 7 16 slot A = 8
2. Calculate “B” chassis input requirements:
(discrete inputs) + (16)(number of analog input channels)
11
=B (round up)
3. Calculate “C” chassis output requirements:
(discrete outputs) + (16)(number of analog output channels)
6
=C (round up)