I am trying to use 5 ADT7x20 Eval Boards(with adt7420 external board) to monitor the temperature at 5 locations within a room. However, when I connect more than one ADT7x20 to the computer via the usb cable and run the software, sometimes it shows "USB communication failed".
However, this error sometimes do not show up if I changed the sequence of plugging in usb ports and opening up new process of the software. Moreover, this error sometimes show up and sometimes do not even if I follow that exact same sequence. Is there any way to reliably operate more than one of these Eval Boards?
I'm afraid this board wasn't designed with the aim of connecting more than one board to the same PC. If you connect two or more boards to the same PC, conflicts may be obtained as the driver wouldn't be able to address the boards, wouldn't be able to know which board is the software talking to.
Once 5 boards are required to use, I would suggest building your own software for managing the boards. Using the Analog Devices' System Development Platform (SDP) could do this process not very complicated. It allows to use up to six ADT7320 parts through SPI interface, and up to four ADT7420 (two address pins).
You can find more info about SDP in the following link.
System Demonstration Platform | Interposer Boards Controller Boards Daughter Boards | Analog Devices