There are apparently 2 versions, the 014 has an internal shunt and is connected in series for loads up to 10A and the 016 uses an external CT to read up to 100A.
This link has a bit more info
it says the 2 models share the same “communication module” and details the modbus registers etc. it implies you can have up to 246 of these connected via modbus-RTU.
It also shows them as having opto-couplers (see the block diagrams) and I notice there are ce and fcc logo’s on the labeling on the underside of the case with the connection diagram.
I also found this zipped info, the Word doc seems to be the same detail as on the webpage I linked above, but i haven’t looked at the rest (open at your own peril!)
PZEM-014 and 016 software in English.zip (2.2 MB)
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