This question uses Google Translate. Therefore, some sentences may cause misunderstanding, so if you have any questions, please ask. I'm sorry for the trouble. Thank you in advance.

Thank you for your reply, ssmith_c. Let me ask the question again to better understand. The requirements are as follows: ・A graph app to see changes in data ・measured data is about 2 bytes. ・measurement time is more than 24 hours. ・I want to obtain samples as finely as possible. Let me ask again, taking the above into consideration. ①Is iBeacon possible even if the app is in the background? ＞If I were trying to make a data logger, I'd log on the device... ②Does "log on the device" mean a connection via GATT communication? Also, does this refer to "b.", which ssmith_c answered?