Allen-Bradley 1791 CompactBlock Guard I/O is a distributed safety I/O block for EtherNet/IP (1791ES) and DeviceNet (1791DS) that brings TÜV-certified SIL3 safety I/O out to the machine, close to the hazard. Unlike in-cabinet POINT Guard I/O, it is a standalone block with built-in 24V DC power.

When is a distributed safety block the right call?

When the hazard sits far from the main cabinet — a remote cell, a guarding station, a robot work envelope — homerunning every safety device back to a central safety rack means long cables and a crowded enclosure. CompactBlock Guard mounts at the cell on DIN rail with removable terminals and built-in power, so safety lives where the risk is and CIP Safety links it to GuardLogix over EtherNet/IP. The alternative — a centralized safety rack — forces every safety device onto one long homerun.

What safety scope does it cover?

The EtherNet/IP blocks (1791ES) offer single- or dual-channel safety inputs and standard pulse-test outputs, with two RJ45 ports supporting linear and Device Level Ring topologies for cable-break resilience. They are TÜV-certified as a system with GuardLogix to SIL3 / Cat. 4 / PLe, and include point-level diagnostics so a faulty input is isolated without tearing down the cell. RIUP (removal under power) lets a block swap without a full safety shutdown when proper procedures are followed.