Detailed description   
2.4 Starting up the PLC program 
  Power Line Basic PLC Program (P3) 
2-22  Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0 
NC variables 
The latest NC VAR selector can be used for each NC software version (even earlier 
versions). The variables can also be selected from the latest list for earlier NC software 
versions. The data content in DB 120 (default DB for variables) does not depend on the 
software version, i.e., selected variables in an older software version must not be reselected 
when the software is upgraded. 
2.4.8  I/O modules (FM, CP modules) 
Special packages for STEP7 are generally required for more complex I/O modules. Some of 
these special packages include support blocks (FC, FB) stored in a STEP7 library. The 
blocks contain functions for operating the relevant module which are parameterized and 
called by the user program. In many cases, the FC numbers of the CP and FM module 
handling blocks are also included in the number range of the basic program for the 810D and 
840D systems.  
What action can be taken if such a conflict occurs? 
The block numbers of the basic program must remain unchanged. The block numbers of 
handling blocks can be assigned new, free numbers using STEP7. These new blocks (with 
new FC numbers) are then called in the user program with the parameter assignments 
required by the function. 
2.4.9  Troubleshooting 
This section describes problems which may occur, their causes and remedies and should be 
read carefully before hardware is replaced. 
 
Errors, cause/description and remedy 
Serial 
no. 
error 
inform
ation 
Error  Cause/description  Remedy 
1  No 
connecti
on via 
MPI to 
PLC. 
The MPI cable is not connected 
or is defective. 
 
 
 
 
 
 
The STEP 7 software for the 
MPI card may not be configured 
correctly. 
Test: Create a link with the programmer in the 
STEP 7 editor by means of connection 
"Direct_PLC". A number of node addresses 
must be displayed here. If they are missing, 
the MPI cable is defective or not connected. 
 
In Windows 95 versions of STEP 7, the 
hardware must be checked in the Control 
Panel; the PC/PG interface configuration 
should also be checked as well.