Two types of the connection methods are available for the E10A-USB emulator.
Connect a UVcc terminal to a H-UDI port connector (recommended)
Do not connect a UVcc terminal to a H-UDI port connector (the same method as E10A emulator).
E10 A-USB recommends Method.1 which connects UVcc of a target system to prevent leakage current from the E10 A-USB emulator.
When the power of the E10A-USB emulator is on ( E10A-USB emulator is being inserted into your PC, and it is on), and a target system is off, the line voltage of the target device (target system) may become higher around 1.2V to1.4V than normal due to the leakage current from the E10A-USB emulator. This may disable power-on reset. Therefore, Method 1 is recommended.