What's the Function of MA5683T and MA5680T?

'The MA5623AR extended subrack can be considered as the extension service board for the
primary subrack of the MA5680T/MA5683T. The primary subrack manages the MA5623AR
extended subrack in the same way as it manages its service boards. The MA5623AR extended
subrack provides the same functions as the VDSL2 board of the primary subrack. It connects to
the ETHB board through the GE upstream port, cascading the primary subrack.
The MA5623AR extended subrack supports the following functions:

•  48-channel VDSL2 access service.
• Vectoring.
• Port protection
• 2-pair VDSL2 bonding when the 8a, 8b, 8c, or 8d profile is used.
• Single-ended loop test (SELT)
• Metallic loop test (MELT)
• VDSL2 8a, 8b, 8c, 8d, 12a, 12b, and 17a profiles
• G.992.1 Annex A, G.992.3 Annex A/B/L/M, G.992.5 Annex A/B/M, G.993.2 Annex A/B
• G.INP physical layer retransmission

NOTE
In bonding mode, the G.INP physical-layer retransmission is not supported.

• Temperature query and high-temperature alarm
• Automatic power shutdown in case of a high temperature

NOTE
The MA5623AR extended subrack supports –48/–60 V DC and 220 V AC input power. The MA5623AR extended subrack that supports 220 V AC input power is used as an example in the following figure.

More related:

When the NMS Fail to Synchronize ONUs.

When Prewarning on Service Unavailability of H806GPBH & H806GPBD Boards of MA5600T

When Display Change of Service Ports and Service Failure in the MA5600T?