What are the advantages and disadvantages of using acknowledged service for Network Variable updates? (KB208) – Knowledge Base

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What are the advantages and disadvantages of using acknowledged service for Network Variable updates?

Solution

Acknowledged service can potentially increase the use of bandwidth depending on whether you use one-to-one or group connections. One needs to keep in mind that all of the devices receiving the update will have to acknowledge the delivery by sending back a message to the source device, if one of those acknowledgements doesn't make it to the source device then the source device will have to retry and send the update to the entire group.

Acknowledged service is required if the sender device needs to act when the receiver device fails to acknowledge the reception of the message. For example, Device A sends an acknowledged message to Device B. If Device B does not respond with an acknowledgement within a predefined period of time (automatically set by an LNS based network management tool), then Device A tries again until it runs out of retries. If the last retry fails, Device A will generate an nv_update_fails() event.

If your Neuron C code does not handle the nv_update_fails() event, then using acknowledged service is probably a waste of bandwidth since you don't take any kind of corrective action when the device cannot communicate with the target. In those situations, you can just make use of the unacknowledged - repeated service, this is particularly advantageous for groups connections since the receiving devices will not have to acknowledge the delivery of the message.

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