Leuze electronic MSI 400 Series Manual page 46

When this method is used, the data are returned in the response to the data request. The PLC requests
data by accessing the receiving data address of the MSI 430 module via a read-holding-register tele-
gram.
• The master receiving method gateway writes to the PLC (auto-update, gateway as master)
When the MSI-EN-MOD module sends data to the PLC, these are immediately written to a memory loc-
ation in the PLC.
• Slave transmission method - PLC writes (gateway as slave)
With this method, the PLC sends telegrams to the MSI 430 module to write to the output data sets. For
this purpose, the PLC writes data into defined addresses.
• The master transmission method gateway reads from the PLC (auto-update, gateway as master)
With the master transmission method, the MSI 430 module polls the PLC for the output data sets.
NOTICE
i
The configuration is regarded as faulty when the IP address of the PLC is zero and the read
transfer mode and/or write transfer mode has been set for the master.
The number of possible connections to the PLC depends on whether the MSI 430 module is operated as a
master or as a slave. Depending on the setting, up to 6 PLCs can simultaneously address the MSI 430
module.
Tab. 6.1: Maximum number of possible Modbus TCP connections for the individual operating modes
Operating mode of the MSI 430 module
Output data (to PLC): Gateway writes
Input data (from PLC): Gateway reads
Output data (to PLC): Gateway writes
Input data (from PLC): PLC writes
Output data (to PLC): PLC reads
Input data (from PLC): Gateway reads
Output data (to PLC): PLC reads
Input data (from PLC): PLC writes
The following table describes the configuration, depending on the transmission method:
Gateway is master
Tab. 6.2: Configuration directive – gateway as master
Essential settings in the gateway configuration
(via MSI 430)
Choose Gateway writes to tag/file and/or Gate-
way reads from register to configure the gateway
as a master.
Select which data are to be written to the PLC or
read from it.
Define where the selected data in the PLC memory
are to be written to: Enter the register address(es).
Example: "40001" and/or you can determine from
which location in the PLC memory the selected data
are to be read: Enter the register addresses.
Choose how often these data are to be transmitted. –
Leuze electronic
Maximum number of connections
1 outgoing connection
1 incoming connection
1 outgoing connection
6 incoming connections
6 outgoing connections
1 incoming connection
6 outgoing connections
6 incoming connections
Settings required for the PLC program and/or in
the Modbus TCP configuration tool
–
–
Ensure that the addresses allocated in the MSI 400
are available and that they contain the data inten-
ded for the MSI 400- system.
MSI 400
Modbus TCP gateway
46