Technical information
3/12
Functions (continued)
Functions (continued)
Global Data service
The Global Data service performs data exchanges in real time between stations
belonging to the same distribution group. It is used to synchronize remote applications,
or to share a common database between a number of distributed applications.
Exchanges are based on a standard producer/consumer protocol, guaranteeing
optimum performance with a minimum load on the network. This RTPS (Real Time
Publisher Subscriber) protocol is promoted by Modbus-IDA (Interface for Distributed
Automation), and is already a standard adopted by several manufacturers.
Characteristics
A maximum of 64 stations can participate in Global Data within a single distribution
group. Each station can:
Publish one 1024-byte variable. The publication period can be configured from
1 to n processor master task (Mast) periods.
Subscribe to between 1 and 64 variables. The validity of each variable is controlled
by status bits (Health Status bits) linked to a refresh timeout configurable between
50 ms and 1s. Access to an element of the variable is not possible. The total size of
subscribed variables amounts to 4 K contiguous bytes.
To further optimize the performance of the Ethernet network, Global Data can be
configured with the “multicast filtering” option which, together with switches in the
ConneXium range (see pages 3/26 to 3/37), broadcasts data only to Ethernet ports
where there is a Global Data service subscriber station. If these switches are not
used, Global Data is sent in “multicast” mode to all switch ports.
Global Data service diagnostics
The diagnostic screens use a colour code to show the Global Data status:
Configured/not configured/faulty.
Published/subscribed.
Global Data service diagnostics can be performed in one of five ways:
Via the application program from a specific PLC data zone.
From the setup software debug screen.
From the PLC system diagnostic function displayed by means of an internet
browser on a PC station.
Using the TCS EAZ 01P SFE10 ConneXview diagnostic software.
Using standard SNMP manager software.
b
b
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Modicon Quantum
Modicon Premium
Modicon Premium
Modicon M340
Distribution group 1
Data exchange 4 KB max.
Data exchange 4 KB max.
Distribution group 2
IP multicast 239.255.255.251
IP multicast 239.255.255.250
Ethernet Modbus/TCP
Modicon Quantum
Modicon Premium
Modicon Premium
Modicon M340
Distribution group 1
Data exchange 4 KB max.
Data exchange 4 KB max.
Distribution group 2
IP multicast 239.255.255.251
IP multicast 239.255.255.250
Ethernet Modbus/TCP
Modicon M340 automation
platform
Ethernet Modbus/TCP network
Ethernet Modbus/TCP communication services
Processors:
page 1/2
I/O:
pages 2/2 and 2/14
Software:
page 4/2
Ruggedized Modicon M340 modules:
page 6/2
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