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CTI 2572 Installation and Operation Guide
66
A given module may produce multiple data sets and consume multiple data sets. In a typical
DataShare application, each module might produce a single data set, and consume one or more data
sets produced by other modules.
6.2. Implementation
Configuring the 2572 module
The DataShare facility is enabled by setting Switch 3 on Switchblock SW2 to the ON position.
When DataShare is enabled, the Ethernet transceiver is enabled for multicast and the following
restrictions are imposed on the use of other protocol managers:
CAMP TCP Server: Limited to one connection
CAMP UDP Server: Not Available
For PLC scan times equal to or greater than 12 ms, you can start any combination of eight DataShare
producer and consumer instances.
NOTE:
For PLC scan times less than 12 ms, you should not start more than two logic triggered producers.
See Start Producer Instance on page 67.
Although other Protocol Managers may be started concurrently with DataShare, you should be aware
that they impact performance because they compete with DataShare for module resources and access
to the PLC. To avoid unacceptable performance, you should limit the number of instances started
and the rate at which messages are sent.
Consumer Packet Buffering
Since DataShare is an unconnected protocol, there is no provision for flow control. Therefore, the
producer(s) may generate packets at a rate that exceeds the consuming module’s ability to update the
PLC. In the case of an overrun condition, DataShare will deliver the most-recently-received packet to
the PLC.
For each Data ID, the software will buffer one incoming packet. While one data packet has been sent
to the PLC, the software will allow an incoming packet to be written to this buffer. Should another