What it is in the panel
The ABB 1SAP210600R0001 is the TU551-CS31 interface terminal unit for the CS31 protocol — it terminates the bus wiring at the I/O rack and provides a labelled landing strip for distributed I/O drops. Function is stated as for CS31 protocol with screw terminals, so the wiring side is a conventional rising-cage or screw clamp that a wireman can torque with a standard blade — no special tooling, no ferrules required on solid conductors. Supply voltage is 24 V DC, drawn from the same PSU feeding the rest of the slice; no independent feed is specified.
Where it physically lives
Degree of protection is IP20, so the TU551 is a cabinet-resident device — it sits inside a closed enclosure behind the panel door, not out in the field. Ambient air temperature for operation is 0…+60 °C, which is the standard cabinet interior envelope; derating kicks in only if the enclosure is unventilated and packed with heat-generating siblings, but the device itself does not impose a tighter window. For field-side mounts, conduit entries and a NEMA-rated cabinet carry the real IP work; the IP20 figure on the TU551 is the panel-internal rating and is the correct number to spec against for the indoor cabinet build.
Production status and sourcing posture
Lifecycle status for 1SAP210600R0001 is recorded as active, so the BOM line does not need a last-time-buy flag and a panel currently spec'd on this terminal unit can be re-ordered against ongoing production.
What the buyer actually takes away
For a procurement line already calling out the TU551-CS31 with screw terminals on a CS31 distributed-I/O build, the 1SAP210600R0001 is the order code that closes the BOM: active, RoHS/REACH-declared, 24 V DC, IP20, 0…+60 °C operation. Spec it in by that exact code where the wiring schedule calls for screw terminations; if the wiring schedule was originally drawn around the spring-terminal TU516, the 1SAP212000R0001 is the same-function equivalent but it is not a no-rewire swap.