can you elaborate on the need for that? Because that would mean that you would track the performance data while it is up, and then stop it once it is down, and start it again when it goes up.
If the motivation is to save storage, I don't think it would have a lot of impact. Because if the port is down, the tracked metrics (like utilization, RX/TX bitrates,...) are static, and in that case the trend logging in DataMiner is smart enough not to continuously store those data points individually.
Just trying the understand the underlying thought for this question.