Can the TX of Transceiver-A be routed to the RX of Transceiver-B internal to the FPGA

[Altera_Forum]

Hello, 

 This question is for both the Stratix II GX High Speed Serial Transceivers and the Stratix IV GX High Speed Serial Transceivers   Can the TX of Transceiver-A be routed to the RX of Transceiver-B internally to the FPGA?   Thank you for your help,

[Altera_Forum]

Hi, 

 According to my experience with stratix II(not GX) the answer is no, since Rx needs LVDS inputs from pins. But I managed to do that in a wrapper testbench by connecting them externally and also looped back externally in actual hardware without problem.  Kaz

[Altera_Forum]

Yes. The transceivers support an internal loopback mode TX->RX. This is an option that you can set in the megawizard when creating your transceiver instance. 

 Note however that there is no way to loop in the reverse direction (RX->TX).  Jake

[Altera_Forum]

Doesn't the loopback feature only work within a single transceiver? What I want to do is go from one transceiver's TX to different tranceivers's RX inside the FPGA so that I can intercept the signal between the two with some programmable logic. 

 Is that possible?   Thanks again.

[Altera_Forum]

I'm sorry. I didn't read your initial post closely enough. You are correct. The loopback is only for a single transceiver. 

 The circuitry does not physically exist to loop between transceiver channels within the FPGA.  Jake

[Altera_Forum]

Ok, thank you, that is what I needed to know.