TN0001

[ISS Support Case] HMI Communication Loss

Client reached out due to two of several HMI nodes loosing communication intermittently. When reviewing the logs I observed several instances of Suitelink suspend and resume messages. This indicates an overload condition generally. SuiteLink handles the possible over-flooding of its write buffer in the above condition by posting a message to itself every one hundred milli-second by default. This message estimates the depth of the message queue. If the message queue is too deep then SuiteLink generates SUSPEND events message on all connected clients and servers. When the message queue falls to a minimum depth, SuiteLink sends a Resume event message to its clients and servers. If a PC or network gets busy for any reason and can not handle the suitelink traffic, a suspend event will occur and suitelink is supposed to stop sending data until it receives a resume event.