Allen-Bradley micrologix 1500 Reference Manual

Publication 1762-RM001C-EN-P
4-8 Programming Instructions Overview
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.
In this example, the controller uses the following addresses:
Operand Base Address Offset Value in N7:3 Working Address
Source A N7:0 20 N7:20
Destination N7:0 20 N15:20
Indirect
Addresses
Working
Addresses
ADD
Add
Source A N7:[N7:3]
Source B 25
Dest N15:[N7:3]
ADD ADD
Add
Source A N7:20
Source B 25
Dest N15:20
ADD

Allen-Bradley micrologix 1500 Specifications

General

Processor Type	16-bit
Programming Language	Ladder Logic
Mounting	DIN rail or panel mount
Programming Software	RSLogix 500
Communication Ports	RS-232
Power Supply	24V DC
Operating Temperature	0°C to 55°C (32°F to 131°F)
Controller Type	Programmable Logic Controller (PLC)