Interface problems in Multimaster mode often occur if you are not using one of the two following RS232/PPI cables which you should be using with STEP 7 Micro/WIN as from V3.2 SP4.
|Intelligent RS232/PPI cable with built-in RS232/RS485 converter
|Intelligent USB/PPI cable with built-in USB/RS485 converter
If you use the above cables, it provides Multimaster functionality.
Problems in Multimaster mode when using an RS232/PPI cable that are attributable to too long a response time by the COM interface on the PC side can be cleared as follows:
||Right-click on the "Workstation" icon and then select "Properties".|
||Go to the "Hardware" tab and open "Device Manager".|
||Double-click on "Connections (COM and LPT)" to open the subtab containing the different connections of the PC.|
||Double-click on the port used for PPI communications.|
||In the "Connection Settings" tab select the "Advanced" button.|
||In the dialog box "Advanced settings for COM(X)" you select the lowest values for receive and transfer buffer and then acknowledge with "OK".|
||You must restart the computer to activate the new settings.|
When using Windows NT with a PC/PPI cable, no other masters should be present on the network. So you cannot make the settings described above in Windows NT. In this case you should choose an MPI/PROFIBUS card (see Entry ID: 22634774).