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Each fiber in the pigtail corresponds to data coming from a separate lpGBT (verification needed for RX 3 and 4):

lpGBT	VTRX+ fiber	FELIX fiber
1	red (7)	TX 1
1	white (6)	RX 1
2	slate (5)	RX 2
3	brown (4)	RX 3
4	green (3)	RX 4

Note that the Optoboard VTRX+ fiber pigtail MT ferrules connection to MPO12-LC fiber splitter is a simple slip on which requires careful manual recognition of right polarity (see ITkPixV1 readout page) which can easily slip off but prevents accidental large force breaking the fiber. It is advisable to always check the link light level with  flx-info podpower  to verify the fiber link is healthy (>700uW). How the VTRX+ fiber pigtail lines are structured is described in the Optosystem Interface document AT2-IP-GM-0010 (Table 4) with 5 out of 12 fibers active per optoboard. How the FELIX MPO24 port is structured and fanout with MPO24->2xMPO12→LC splitters are described in the FELIX readout and Direct FELIX confluence pages.     

Current firmware allows only 2 lpGBTs to be readout, such that the link alignment string is fixed to x0000000300000000 for channels 00 and 01 in unaligned state. Alignment can be checked using data from module RX 0 (L0 on miniDP-SMA) after module configuration, giving the following link alignment strings independently of which e-links are subscribed on felixcore startup:

There is a broken connection in L1 UPLINK 02 in the miniDPERF-SMA board or within the optoboard itself.

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