Installation manual

Publication 1747-RM001G-EN-P - November 2008
E-10 Data File Organization and Addressing
Specifying Indexed Addresses
The indexed address symbol is the # character. Place the # character
immediately before the file-type identifier in a logical address. You can use
more than one indexed address in your ladder program.
Enter the offset value in word 24 of the status file (S:24). All indexed
instructions use the same word S:24 to store the offset value. The processor
starts operation at the base address plus the offset. You can manipulate the
offset value in your ladder logic before each indexed address operation.
When you specify indexed addresses, follow these guidelines.
• Make sure the index value (positive or negative) does not cause the
indexed address to exceed the file type boundary.
• When an instruction uses more than two indexed addresses, the
processor uses the same index value for each indexed address.
• Set the index word to the offset value you want immediately before
enabling an instruction that uses an indexed address.
Example of Indexed Addressing
The following Masked Move (MVM) example uses an indexed address in the
source and destination addresses. If the offset value is 10 (stored in S:24), the
processor manipulates the data stored at the base address plus the offset.
ATTENTION
Instructions with a # sign in an address manipulate
the offset value stored at S:24. Make sure you monitor
or load the offset value you want prior to using an
indexed address. Otherwise unpredictable machine
operation could occur with possible damage to
equipment and/or injury to personnel.