Rockwell Automation 1747-PCINT API Software for 1746 I/O - Manual (Page 51)

Configuring I/O Modules 5–3
Publication 1747-6.5.3 June 1998
Using M0-M1 Files
and G Files The 1746 I/O PCI Interface uses M0-M1 files and G files to download configuration
information to specialty I/O modules. The following descriptions describe the basics
of M0-M1 and G files. For detailed information, see the user manual for the specialty
I/O module you are configuring.
M0-M1 files
M0 and M1 files are data files that reside in specialty I/O modules only. There is
no image for these files in the dual port memory (like the discrete input and output
image files). The application of these files depends on the function of the particular
specialty I/O module. Your application program initiates the transfer of these files.
Each transfer is a single request or an API call. With respect to the 1746 I/O PCI
Interface, the M0 file is a module output file (a write-only file) and the M1 file is a
module input file (a read-only file).
You can address M0 and M1 files in your application and they can also be acted
upon by the specialty I/O module - independent of the processor scan.
G files
Some specialty modules (such as the 1747-SN) use configuration files, which act
as the software equivalent of DIP switches.
The data you enter into the G file is automatically passed to the specialty I/O module
when you enter Scan mode.