Usually a LED display hub card is used to connect LED module and receiver card.

Then, What’s hub card?

The HUB card used in LED display is a passive HUB.
It’s designed for LED receiver card’s signal distribution,and hub card can help the signal distribute in 4 ,6, 8 or 12 output.
In this way,a reciver card can be connected to many rows of LED modules.

Ordinarily,there are 2*50  pin hole on the one side of HUB card in order to connect to receiver card.
At the other side,there are pin holes like 4*20,6*20 or 8*16 to connect to rows of LED modules.