Rockwell Automation AADvance Controller Safety Manual User Manual

Page 53

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Document: 553630
ICSTT-RM446K-EN-P Issue: 10

3-19

Configuring Variable Bindings

The bindings configuration includes the value of an age timeout (MaxAge).

This timeout defines the maximum age of data that can be used by a consumer
system. Data older than the defined timeout is discarded and the system

continues using its last state value. Once disconnected the consumer attempts

to re-establish a connection to the producer by sending a connection request
at ConnectTimeout intervals. The consumer continues to send connection

requests until a connection is established.
The configuration also includes a timeout value for a consumer

BindRespTimeout value for the binding data response from a producer.
Failure to receive a valid response containing fresh data within this timeout

causes the consumer to disconnect from the producer. The number of retries

that are attempted before a consumer disconnects depends on the configured
values for the parameter MaxAge.
The configuration also includes a timeout value BindReqTimeout, which is

used by a producer system to timeout binding data requests from a consumer
system. Should a producer fail to receive a binding data request from a

consumer within this timeout value, the link to the consumer system is closed.

The consumer system, if still functional, will timeout the link from its end.
An UpdateTimeout value can also be configured. This timeout is used in
both the consumer and producer resources during an on-line update. During

an on-line update all binding connections are closed. The SNCP binding driver

then restarts with the potentially new binding configuration. This timeout value
is the time in which the consumer must re-establish its binding connections.
Timeout values should be set within the fault tolerant capabilities of the

bindings network, so the system can still respond within the required PST. The
network propagation time must be included in the timeout period calculations,

and should be verified after each change to the network configuration.
Two function blocks are provided that make the overall status of the bindings
communication subsystem available to the application — one indicates

consumer status (KvbConsNetStatus) for a specific bindings link (identified by

the Producers Resource Number and IP Address, the other producer status

(KvbProdNetStatus) for a specific bindings link (Identified by the Consumers
Resource Number and its IP Address). In addition to these, an error variable

can be configured to report error codes for the bindings links to the

application.
Note: The Consumers Network bindings parameters (i.e. timeout values) are

those located in the Producing Resource.