Allen-Bradley MicroLogix 1400 Instruction Manual page 100

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98 Programming Instructions Overview
Publication 1766-RM001A-EN-P - October 2008
Indirect Addressing Example
An equivalent example using indirect addressing is shown below. In place
of using the index register, S:24, the user can designate any other valid
word address as the indirect address. Multiple indirect addresses can be
used within an instruction.
The following ADD instruction uses an indirect address in the Source A
and Destination addresses. If the indirect offset value is 20 (stored in
N7:3), the controller uses the data stored at the base address plus the
indirect offset to perform to instruction.
Indirect
ADD ADD
Add
Source A N7:[N7:3]
Source B 25
Dest N15:[N7:3]
In this example, the controller uses the following addresses:
Table 4.2
Operand Base Address
Source A N7:0
Destination N7:0
Working
Add
Source A
Source B
Dest
Offset Value in N7:3 Working Address
20 N7:20
20 N15:20
ADD ADD
N7:20
25
N15:20