MVI46-PDPS ♦ SLC Platform
Reference
Profibus DP Slave Communication Module
User Manual
ProSoft Technology, Inc.
Page 43 of 53
5.2.4 Backplane Data Transfer
The MVI46-PDPS module communicates directly over the SLC backplane. All data for
the module is contained in the module's M1 file. Data is moved between the module and
the SLC processor across the backplane using the module's M-files. The SLC scan rate
and the communication load on the module determine the update frequency of the M-
files. The COP instruction can be used to move data between user data files and the
module's M1 file.
The following illustration shows the data transfer method used to move data between the
SLC processor, the MVI46-PDPS module and the PDPS network.
User File
User File
User File
M0
M1
PROFIBUS
Data
Input Data
Output
Data
Input Data
Output
Data
Ladder
Logic
M-Files
PROFIBUS
Slave
PROFIBUS
Master
M1 Status
Data
All data transferred between the module and the processor over the backplane is
through the M0 and M1 files. Ladder logic must be written in the SLC processor to
interface the M-file data with data defined in the user-defined data files in the SLC. All
data used by the module is stored in its internal database.
User data contained in this database is continuously read from the M0 file. The
configuration data is only updated in the M1 file after each configuration request by the
module to the SLC. All data in the M1 file is available to devices on the PROFIBUS DP
networks. This permits data to be transferred from these devices to the SLC using the
user data area.
