Omron SYSMAC C20K Operation Manual page 29

Internal Relay (IR) Area
The tables on the following pages show the possible configurations for a
K-type PC. Although the tables branch to show the various possibilities at
any one point, there can be no branching in the actual PC connections. You
can choose either branch at any point and go as far as required, i.e., you can
break off at any point to create a smaller PC System.When implementing a
system there is a physical restriction on the total cable length allowable. The
sum of the lengths of all cables in the system must be limited to less than 1.2
meters.
The tables also show which words will be input words and which words will
be output words. All of these are determined by the position of the Unit in the
configuration except for the C4P and C16P Expansion I/O Units, in which
case the model of the Unit determines whether the words are input or output.
The symbols used in the table represent the following:
C20K/C28K
C20K or C28K CPU Unit
Input Output
C40K/C60K
Input Output Input
C4K/C16P
C4P or C16P Expansion I/O Unit
In/Output
C20P/C28P/TU/LU,
C20P Expansion I/O Unit, C28K Expansion I/O Unit,
Analog Timer Unit, or I/O Link Unit
Input Output
C40P/C60P
Input Output Input
C40K or C60K CPU Unit
Output
C40P or C60P Expansion I/O Unit
Output
Section 3-3
17