This is a Mac OS X 10.9 and later issue only.

Among the number of power-saving features that Mac OS X 10.9 introduced, the App Nap feature overrides an application’s request to use the CPU and ports. If the feature engages during certain data collections using Logger Pro and an interface such as LabQuest, connection to the interface can be lost, ending data collection.

Additionally, confusing connection failures to LabQuest can occur if Logger Pro is invoked and then put behind other windows on the Mac for a few minutes. Connecting a LabQuest to the computer in this state will result in Logger Pro not seeing the LabQuest until it is brought to the foreground. Sometimes it can take a dozen seconds or more for Logger Pro to wake up sufficiently to see and connect to the LabQuest in this scenario.

To avoid these problems, update to the latest version of Logger Pro if possible. Logger Pro 3.9 (and above) prevent App Nap during critical data collection periods while allowing it when no data collection is taking place. In earlier versions of Logger Pro running on 10.8 or 10.9, you may explicitly disable App Nap for Logger Pro. Locate the Logger Pro application in the Application folder, single-click it to select, and choose Get Info from the File menu. Select the Prevent App Nap check box. Close the dialog box.

The issue has occurred with Logger Pro 3.8.7 and earlier, as well as Logger Lite 1.7 and earlier.

Logger Pro 3.9 and Logger Lite 1.8 resolve the issue.

Starting with Mac OS 10.10, the Prevent App Nap check box no longer appears. Users should upgrade to Logger Pro 3.9 or later for use on Mac 10.10 and above.