I will do both test again tomorrow and post the results.
Here is some extra information about how other people connected this
meter to their pc with a serial TTL to USB cable (with FTDI chip) :
http://www.domoticaforum.eu/viewtopic.php?f=71&t=6104&start=60
I want to do the same but then with an arduino (mega & ethernet shield).
It's not a silly question but I don't have a scope.
Thank you for your patience, I appreciate your help !!!!