Design 10g Ethernet with Xilinx IP 10g Ethernet subsystem，use sfp+ optical module is ok，change to 10g sfp+ t electrical module，it doesn’t work.IP PCS/PMA block is 10gbase-R, 10g sfp+ t electrical module phy type is 10gbase-T,but I have checked 10g sfp+ t electrical module datasheet,the host interface is XFI,so why sfp+ optical module can work,10g sfp+ t electrical module fail.
There are several reasons why this can fail. In no particular order:
Some SFP electrical plugins do not correctly implement the LOS pin functionality. Some reflect the status of the electrical interface on LOS; others have LOS permanently low (= indicating the link is always up, even when it's not).
Most SFP electrical plugins draw a lot more power supply current than their optical siblings. This may lead to current limit or heat issues if the hardware designer didn't allow for the extra current or heat.
Some 10G SFP electrical plugins will downshift to (e.g.) 5Gb/s or 2.5Gb/s or slower depending on the cable quality. N.B. Most only specify a 30m span of CAT6a at 10G. Unless you know your PCS/MAC can handle the downshift, you should disable it by writing to the appropriate SFP registers (or get shorter or better cable).
FEC is done in the SFP plugin. You should disable FEC in your PCS.
Different 10G SFP electrical plugins may use different I2C addresses. I have seen up to three different I2C addresses used on a single plugin. Make sure you have the correct settings for the particular plugin you are using.