Chapter 4
Data File Organization and Addressing
4–21
M0 and M1 files are data files that reside in specialty I/O modules only.
There is no image for these files in the processor memory. The application
of these files depends on the function of the particular specialty I/O module.
For some modules, the M0 file is regarded as a module output file and the
M1 file is regarded as a module input file. In any case, both M0 and M1 files
are considered read/write files by the SLC 5/02 processor.
M0 and M1 files can be addressed in your ladder program and they can also
be acted upon by the specialty I/O module – independent of the processor
scan. It is important that you keep the following in mind in creating and
applying your ladder logic:
Important: During the processor scan, M0 and M1 data can be changed by
the processor according to ladder diagram instructions
addressing the M0 and M1 files. During the same scan, the
specialty I/O module can change M0 and M1 data, independent
of the rung logic applied during the scan.
Addressing M0-M1 Files
The addressing format for M0 and M1 files is below:
Mf:e.s/b
Where
M = module
f = file type (0 or 1)
e = slot (130)
s = word (0 to max. supplied by module)
b = bit (015)
Restrictions on Using M0M1 Data File Addresses
M0 and M1 data file addresses can be used in all instructions except the OSR
instruction and the instruction parameters noted below:
Instruction
Parameter (uses file indicator #)
BSL, BSR
File (bit array)
SQO, SQC, SQL
File (sequencer file)
LFL, LFU
LIFO (stack)
FFL, FFU
FIFO (stack)
M0 and M1 Data Files -
Specialty I/O Modules
