Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 231)

ASCII Module
For PLCĆ3 Proessor
Appendix B
B-9
User program contains 20K words
Channel 1 contains four I/O chassis, with a total of three block
transfer modules including one ASCII module
Channel 2 contains two I/O chassis with no block transfer modules
Channel 3 contains two I/O chassis with one ACII module
Channel 4 is made inactive through processor LIST
You can compute the read or write block transfer times for the
supervisory processor in this example in four steps. Each of the
following steps is explained by an accompanying figure.
1. Diagram the I/O channels of your PC system (Figure B.3),
showing the number of:
block transfer modules in each I/O chassis
block transfer I/O channels
I/O chassis entries in the rack list for each block transfer I/O
channel
active I/O channels per scanner
A block transfer I/O channel is a channel that contains one or more
block transfer modules located in any chassis connected to the
channel.
An I/O chassis can appear more than once in a rack list of I/O
chassis. Count it and the block transfer module(s) that it contains as
often as it is listed.