Rockwell Automation 1336T PLC Comm. Adapter, Series B, FRN 2.xx-3.xx - Manual (Page 64)

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Publication 1336 FORCE–5.13 –– September, 1998
The redundant mode operates as follows:
1. The respective PLC controller transfers data from the output
image table of each PLC controller to the PLC Communications
Adapter Board.
2. The RIO redundant channel number parameter (parameter 427)
determines which PLC controller’s output is made available to
the drive via parameters 322 through 329.
3. Each PLC controller input image table receives data from the
drive via parameters 351 through 358.
4. Block transfer messages from both drives are processed as normal
if both channels are configured for block transfer.
The RIO scanner mode allows you to control a logical rack of I/O
data from a single drive. The I/O data that makes up the logical rack
may be located on multiple devices, but the drive using RIO scanner
mode sees the logical rack of I/O data as a single unit. The drive
keeps track of the devices by using a scan list, which is a list of the
devices to scan.
The RIO scanner scans only one logical rack of data, which is eight
words of I/O data. The logical rack that is scanned can either be a
full rack or any combination of partial racks (such as 1/4 rack, 1/2
rack, or 3/4 rack) as long as the total does not exceed one logical
rack. For example, you could have the RIO scanner scan a 1/4 rack
and a 3/4 rack, but you could not have the RIO scanner scan a 1/2
rack with a 3/4 rack. You could also have the RIO scanner scan less
than a full rack, such as scanning two 1/4 racks.
Using RIO Scanner Mode