5/03
IO-RO16, IO-RO16-L
I / O E x p a n s i o n M o d u l e s
Unitronics Industrial Automation
7
Addressing I/Os on Expansion Modules
Inputs and outputs located on I/O expansion modules that are connected to an OPLC are assigned
addresses that comprise a letter and a number. The letter indicates whether the I/O is an input (I) or an
output (O). The number indicates the I/O’s location in the system. This number relates to both the position
of the expansion module in the system, and to the position of the I/O on that module.
Expansion modules are numbered from 0-7 as shown in the figure below.
0
1
2
3
4
5
6
7
Expansion module
identification number
Adapter
The formula below is used to assign addresses for I/O modules used in conjunction with the M90 OPLC.
X is the number representing a specific module’s location (0-7). Y is the number of the input or output on
that specific module (0-15).
The number that represents the I/O’s location is equal to:
32 + x • 16 + y
Examples
Input #3, located on expansion module #2 in the system, will be addressed as I 67,
67 = 32 + 2 • 16 + 3
Output #4, located on expansion module #3 in the system, will be addressed as O 84,
84 = 32 + 3 • 16 + 4.
EX90-DI8-RO8 is a stand-alone I/O module. Even if it is the only module in the configuration, the EX90-DI8-
RO8 is always assigned the number 7.
Its I/Os are addressed accordingly.
Example
Input #5, located on an EX90-DI8-RO8 connected to an M90 OPLC will be addressed
as I 149, 149 = 32 + 7 • 16 + 5
