Installation manual

Publication 1747-RM001G-EN-P - November 2008
E-22 Data File Organization and Addressing
The COP instruction that follows copies data form an M1 data file to an
integer file. This technique is used to monitor the contents of an M0 or M1
data file indirectly, in a processor data file.
Access Time
During the program scan, the processor must access the specialty I/O card to
read/write M0 or M1 data. This access time must be added to the execution
time of each instruction referencing M0 or M1 data.
Minimizing the Scan Time
You can keep the processor scan time to a minimum by economizing on the
use of instructions addressing the M0 or M1 files. For example, XIC
instruction M0:2.1/1 is used in rungs 1 and 2 of the figure below, adding
approximately 2 ms to the scan time if you are using an SLC 5/02, Series B
processor.
First scan bit. It makes
this rung true only for the
first scan after entering
the Run mode.
XIC instructions in rungs 1 and 2 are addressed to the M0 data file. Each of these instructions
adds approximately 1 ms to the scan time (SLC 5/02, Series B processor).