The issue can be considered closed.  After endless reboots of both SP and SPS, as well as cleaning all pins and sleeves with a fiber brush, both SPS are now recognized and functioning normally. Sigh.
Hi there,  a few weeks ago we got two used CX700 arrays for a laugh of a price. Everything seems fine except this issue:  One SPE does not really recognize its pair of SPS. I cabled it all correctly, the SPS are showing the green LED lit constantly. I attached the RS232-wires which came with the system. SP-A reports the SPS as faulted and an "Invalid serial cable", SP-B flags its SPS as not present with "cabling status is unknown". I tried several cables, built some on my own. All pins are wired correctly, ground connection is present.  Any Ideas on this?  Thanks! -Chris
CX700: SPS not recognized and marked faulted - SPS' green led constantly on