Description
The command "SubscribeTagValue" subscribes the specified tag for monitoring.
Error handling
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When the tag value contains a line break (\n), the value cannot be signaled. An error is signaled.
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When the same tag is subscribed a second time for monitoring, an error is signaled.
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A global monitoring error is signaled with "ErrorSubscribeTagValue". Because no monitoring was set up, there is no need to unsubscribe the tag from monitoring.
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An error relating to the tag value is signaled with
"ErrorNotifyTagValue". Monitoring is set up in this case, but the tag value cannot be signaled for various reasons. Unsubscribe the tag from monitoring when it is no longer needed.
Request
SubscribeTagValue <Tag>
For example: SubscribeTagValue Tag_1
Response
OnSuccess (or partial success):
NotifySubscribeTagValue <Tag> <Quality> <Value>
For example:
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NotifySubscribeTagValue Tag_1 Uncertain 0 -
NotifySubscribeTagValue Tag_1 Good 10 -
NotifySubscribeTagValue Tag_1 Bad 12
OnError:
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Global error:
ErrorSubscribeTagValue <Tag> <Error text>For example:
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ErrorSubscribeTagValue Tag_1 Tag does not exist -
ErrorSubscribeTagValue Tag_1 Subscription already exists
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Error for tag value:
ErrorNotifyTagValue <Tag> <Error text>For example:
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ErrorNotifyTagValue Tag_1 Encoding error -
ErrorNotifyTagValue Tag_1 Value contains newline
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