Allen-Bradley 1734-IB8S POINT Guard I/O 8-Channel Safety Input Module

Eight safety inputs for POINT I/O safety nodes

The Allen-Bradley 1734-IB8S is a POINT Guard I/O safety module with eight sinking safety inputs. It connects emergency stops, light curtains, safety gate switches and other safety devices to a safety controller over a safety network, and it is used together with GuardLogix, Compact GuardLogix or SmartGuard controllers.

The installation sheet states that POINT Guard I/O modules, used as part of a POINT I/O system, distribute safety I/O on a safety-control network that meets the requirements up to and including SIL CL 3 and PLe, Cat. 4, as defined in IEC 61508, IEC 61511, IEC 62061 and ISO 13849-1. The actual rating of a machine depends on the whole safety function, not on one module.

Technical specifications

Electrical and mechanical data

Field power is 19.2 to 28.8V DC (25 mA with no load) from a Class 2 SELV/PELV source limited to 150VA, and the backplane draws 5V DC at 125 mA. The input threshold is 11 to 30V DC at 3.5 mA at 40 °C, or 11 to 28.8V DC at 55 °C. Isolation between the field side and the system is 50V continuous, basic insulation type.

The module has a distinctive red housing so that it is not mistaken for a standard input. Indicators show lock status, power status (green/yellow) and the status of each of the eight channels. Pilot duty ratings are not stated for the test outputs of this module.

Selection and installation

Choose the 1734-IB8S when the safety signals are wired into a distributed node and the controller is a GuardLogix, Compact GuardLogix or SmartGuard type. The module snaps onto a POINT I/O wiring base, and the sheet gives installation steps for the terminal base, the removable terminal block and the module. Configuration, programming and safety reaction time are in the POINT Guard I/O Safety Modules User Manual, publication 1734-UM013, which the sheet cites.

Operating temperature is -20 to +55 °C. Do not mix this module with standard inputs in a safety function unless the safety application and its validation call for it, and do not rely on the data in this page for a safety assessment.

Planning the safety input node

A 1734-IB8S is only one link in a safety function, so its place in the design should be decided together with the risk assessment and the safety requirements specification for the machine or process. List each safety device that will be wired to the module, the controller that will own it and the reaction the safety function must achieve. That list makes it easier to confirm how many POINT Guard I/O modules the node needs and whether spare channels should be kept for later changes.

Field power must come from a Class 2 SELV/PELV source within the limits shown in the specification table. On larger panels it is good practice to document which supply feeds each POINT I/O node, so that maintenance staff can isolate one area without unexpectedly removing power from another safety function.

Panel layout and wiring practice

Because the module is open-style with no enclosure type rating, it has to be installed inside a suitable control panel. Keep safety input cabling neatly segregated from motor and power cables, label every conductor to match the safety circuit drawings, and leave enough space around the node for the removable terminal block to be withdrawn during service. The red housing helps technicians recognise safety modules, but clear panel labelling is still important when standard and safety I/O share the same DIN rail.

Commissioning and validation

Configuration of the 1734-IB8S is done from the safety controller project, following the procedures in publication 1734-UM013. After download, every input channel should be exercised from the real field device rather than simulated, and the response observed both on the module channel status indicators and in the controller. Record each test against the safety function it belongs to.

Validation of the complete safety function, including reaction time and fault behaviour, is the responsibility of the machine builder or plant owner and must be repeated whenever wiring, configuration or firmware changes. Keep the configuration signature and test records with the panel documentation so that later audits can trace exactly what was approved.

Operating environment in Oman and the GCC

The stated operating range is -20 to +55 °C, and the input specification is given separately for 40 °C and 55 °C. In Gulf plants a control panel exposed to direct sun or installed in an unventilated shelter can approach or exceed that upper limit during summer, so panel cooling, shading of the enclosure and the location of the cabinet deserve attention at design stage.

Dust and humidity are the other main concerns. Use enclosures with suitable sealing for the location, keep cable entries closed, and avoid condensation by controlling the temperature difference between the panel interior and the surrounding air. In coastal or chemical areas, discuss the environment with the project engineer when choosing between the 1734-IB8S and the coated 1734-IB8SK named in the specification table.

Maintenance and replacement

Routine checks should include a look at the module status indicators, inspection of terminals for looseness or contamination, and proof testing of each safety function at the interval set by the safety assessment. When a module is replaced, confirm the catalog number and series, follow the replacement procedure in the user manual and repeat the relevant validation tests before the machine returns to production.

Documents and quotation

The sheet 1734-IN016 covers the 1734-IB8S, 1734-IE4S, 1734-OB8S and 1734-OBV2S. Send the 1734-IB8S reference, series, quantity, the safety controller and the required safety level when you request a quotation. Related parts are in PLC & I/O Cards.