Rockwell-automation 5720 DriveLogix System Uživatelský manuál stáhnout pdf (Strana 164)

Publication 20D-UM002C-EN-P - November 2003

7-18 Communicating with Devices on a ControlNet Link

The producer and consumer must be configured correctly for the specified

data to be shared. A produced tag in the producer must be specified exactly the

same as a consumed tag in the consumer.

If any produced/consumed tag between a producer and consumer is not

specified correctly, none of the produced/consumed tags for that producer

and consumer will be transferred. However, other consumers can still access

their shared tags, as long as their tags are specified correctly. One consumer

failing to access shared data does not affect other consumers accessing the

same data.

Maximum number of produced and consumed tags

The maximum number of produced/consumed tags that you can configure

depends on the connection limits of the communication device that transfers

the produced/consumed data.

Each produced tag uses one connection for the tag and the first configured

consumer of the tag. Each consumer thereafter uses an additional connection.

Size limit of a produced or consumed tag

A produced or consumed tag can be as large as 488 bytes, but it must also fit

within the bandwidth of the ControlNet network:

• As the number of connections over a ControlNet network increases,

several connections, including produced or consumed tags, may need to

share a network update.

• Since a ControlNet network can only pass 500 bytes in one update, the

data of each connection must be less than 488 bytes to fit into the

update.

If a produced or consumed tag is too large for your ControlNet network, make

one or more of the following adjustments:

• Reduce the Network Update Time (NUT). At a faster NUT, less

connections have to share an update slot.

• Increase the Requested Packet Interval (RPI) of all connections. At a

higher RPI, connections can take turns sending data during an update

slot.

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Rockwell-automation 5720 DriveLogix System Uživatelský manuál Strana 164