From RSLogix500 help
Indexed Addressing:
Indexed addressing is valid with SLC 5/02, 5/03, 5/04, 5/05 or MicroLogix 1000 processors only.
An indexed address is one which is offset from its indicated address in the data table. Indexing of addresses applies to word addresses in bit and integer data files and also to the preset and accumulator words of timers and counters, and to the length and position words of control elements.
The offset value is contained in word 24 of the status file (S:24). The number in S:24 can be positive or negative.
The indexed address symbol is #. When programming, place it immediately before the file type identifier in the word address. For example #N7:2 is an indexed address.
Warning! The # symbol is also required for addresses in file instructions which also make use of word S:24 to store an offset value. If you are using file instructions in your program as well as indexed addressing, make sure that you load the correct offset value in S:24 prior to using an indexed address that follows a file instruction. Otherwise, unpredictable operation could occur, resulting in possible personal injury and/or damage to equipment.
Indexed addressing does not work in Timers, Counters, or Control files. Indexed addressing is invalid in any file type which consists of multi-word elements.
Data tables are not expanded automatically to accommodate indexed addresses.
RSLogix 500 - Copyright Rockwell Software 2000, 2001, 2002
Indirect Addressing:
Indirect addressing is valid with SLC 5/03 OS302, 5/04 OS401, and SLC 5/05 OS500 and OS501 and MicroLogix 1200 and 1500 processors only.
An indirect address is one that lets you substitute a word or bit number in a logical address with the value in another address. The processor uses the value from the substitute address to form the indirect address. You can use ladder logic to change the value stored at the substitute address.
Enter the substitute address in brackets [ ].
You can use M files to contain values used to calculate indirect address locations.
Example:
B3:[N7:1]/[N7:12] - In this example the word number is stored in integer address N7:1, and the bit number is stored in integer address N7:12.
Warning! Make sure that any indirect address being used in your ladder logic points to a valid data file and/or element. The processor will halt if it encounters an invalid address in Run mode.
Related Topics
RSLogix 500 - Copyright Rockwell Software 2000, 2001, 2002