I apologize for the confusion.
The PTP 820S has three Ethernet data ports and the PTP 820C has two Ethernet data ports.
Let me clarify:
820S
The PTP 820S has five ports: PWR, ETH1, ETH2, ETH3, and MGT.
PWR and/or ETH1 can be used to power the unit.
ETH1 is a copper RJ-45 interface, whilst ETH2 and ETH3 are SFP.
The PTP 820S can have up to three Ethernet interfaces for data. (The MGT port is used to manage the unit, although it can be mangaged via any of the Ethernet ports.)
820C
The PTP 820C has five ports: PWR, ETH1, ETH2, ETH3, and MGT.
PWR and/or ETH1 can be used to power the unit.
ETH1 is a copper RJ-45 interface, whilst ETH2 and ETH3 are SFP.
The PTP 820C can have up to two Ethernet interfaces for data: ETH1 and ETH2.
ETH3 is reserved for MIMO.
(The MGT port is used to manage the unit, although it can be mangaged via any of the Ethernet ports except ETH3.)
If you have PTP 820C applications that require three Ethernet data interfaces, please contact us, and we can provide a solution. (It probably involves taking a few units off the manufacturing line and swapping the SFP interface before it's shipped to you!)
I hope this helps!
Dave