OTG and Active Devices

[metrologist]

Hi All,

I am not all that familiar with OTG other than using it to connect USB memory devices to my tablet. This afternoon I was asked to volunteer my phone for some testing that required an Android OS. My phone was plugged into a measuring instrument via OTG USB cable. The instrument usually uses USB for connecting USB memory devices or remote programming.

I noticed that the home/back LED buttons on my phone were very bright when plugged into the instrument. I was thinking that the OTG cable generally connects passive devices and the phone would power them rather than seeing an input voltage. I wonder if this could be an issue and damage the phone?