The ABB 1SVR440721R1000 is a CL-LET.20DC2 expansion module designed to extend the I/O or function set of an ABB logic relay base. It sits in the PLC Expansion Modules class and is sized to mount alongside the matching logic-relay family on the same DIN rail, so it pulls its supply from the base unit rather than drawing a separate line. Listed mass is 0.09 kgs, which is light enough that DIN-rail fill and pitch — not weight — drive the panel layout call. A typical expansion of this class adds one or two module widths next to the base; the integrator should treat the rail real estate, not the kilograms, as the constraint.
What the class is used for
PLC Expansion Modules of this family are dropped next to a logic relay or compact controller when a small automation job needs more digital inputs, more relay outputs, or a dedicated analog channel than the base unit ships with. They are common in skid panels, pump control boxes, and small machine cells where a full PLC rack would be overkill but the base logic relay has run out of points.
No production-status entry is on file for 1SVR440721R1000, so the official lifecycle posture is unstated in this record.
Adjacent code reference
Three ABB peer codes sit in the same expansion class: 1SBP260100R1001 at 0.09 kgs, and 1SBP260104R1001 and 1SBP260105R1001 at 0.10 kgs each. They are sibling order codes, not verified drop-in alternates for 1SVR440721R1000.