Rockwell Automation 1747-PCIS API Software - Open Controller - Manual (Page 57)

Publication 1747-UM002A-US-P - June 2000
Configuring I/O Modules 5-3
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.