What the card is
The ABB 1SAP284100R0001 is a DX581-S distributed automation digital input/output module that combines safe digital I/O and pulse outputs on one carrier, intended as an expansion drop on an ABB distributed I/O backbone rather than as a standalone PLC. It is positioned under PLCs and HMIs / PLCs and Accessories / PLC Expansion Modules, which is the line a panel builder browses when a safety-relevant I/O island has to sit next to the controller rather than on a remote bus.
Channel layout and SIL class
The card carries 8 digital inputs that satisfy SIL2 and 4 of those 8 also satisfy SIL3, with the same dual-rating logic on the 8 digital outputs at 24 VDC, and a configurable I/O count of 8 — meaning half the DIO block can be re-tasked per channel in the engineering tool. Pulse outputs number 4, and that pulse capability is what makes the DX581-S a fit for frequency or counter applications that a plain DI/DO cannot service. The input budget sits at 7 mA per channel and supports a configurable input delay of 1 to 500 ms, which covers debounce on mechanical contacts down to fast event capture on solid-state sensors without an external conditioning relay.
Power, output drive, and signal envelope
Supply is 20.4 to 28.8 V DC; output drive is transistorized at 0.5 A per channel over the same 20.4 to 28.8 V DC window. Inputs are DC with a maximum input voltage span of 0 to 30 V, and the I/O type is DC on both sides — there is no AC handling on the outputs of the DX581-S. The enclosure is IP20, which places the module in the cabinet-mount class only; field cabinet selection has to provide the IP54 or better environment that the surrounding wiring and terminations need.
Where it sits against same-class siblings
For applications that need 230 VAC outputs, the 1SAP245200R0001 (DX522) provides 8 digital inputs plus 8 relay outputs at 3 A and 195.5 to 276 V output — a relay-output alternative that is functionally different in switching element, not in channel count, and is not a pin-for-pin swap with the DX581-S. The 1SAP212000R0001 (TU516) is a terminal unit for analog and 24 VDC digital modules with spring terminals and a 0 to +60 °C operating envelope — a carrier accessory rather than a functional substitute, used as the backplane the DX581-S mounts onto.
Integration and sourcing note
Mechanical and software integration follows the standard ABB distributed I/O recipe: the DX581-S drops into the matching terminal unit, and the 20.4 to 28.8 V DC supply feeds the carrier within the rated window. Hold the unit on the grid applies in the safety sense: because the SDIs are rated SIL2 (four of them SIL3) and the SDOs are rated SIL2/3, the same card can serve a single SIL2 loop without an extra safety relay — provided the application safety case is built on that dual-rating rather than assumed. For a BOM line keyed to 1SAP284100R0001, the part is specified to order against an RFQ; the active lifecycle status and the regular channel both keep the line on a standard replenishment path, and a panel builder specifying a replacement against the DC532 or DX522 needs to re-check the SIL and output-type assumptions before sign-off.