What is it?

DEVDET~1.EXE is a truncation of devdetect.exe, this file is associated with ACD System's image managment software.

What does it do?

Monitors the system for devices, if one is connected and devdetect.exe is running, ACD systems Image managment software can open and view, download or otherwise "manage" images and media from the device.

From ACD Systems:
"The first time you connect a device to your computer, if there are files on your device, the Device Synchronization Wizard will work in conjunction with ACDSee's Device Detector to configure and profile your device. To perform the initial configuration, Device Detector needs to be active. If you choose not to use Device Detector, you can acquire your images using the Acquire Wizard"

More info:

Read more about ACD System's image management software @ ACDsystems.com