Application Scenario
A packaging-machine builder was standardizing its panels on ArmorPoint I/O but kept running into the same problem: the main conveyor and the safety-interlock sensors sat on 24 V DC, while the existing plant wiring to the old relay cabinet was 120 V AC. Two different input cards meant two different module types to stock, two sets of spares, and a wiring discipline that nobody could remember during a midnight breakdown.The builder consolidated on the 1738-IB8M8. All eight inputs land on one module regardless of whether the device is a 24 V DC proximity switch or a 120 V AC limit switch, and the 8…132 V range absorbed the mixed wiring without a single converter. The electronic fuse per terminal meant the one shorted sensor that used to disable the whole card now disabled exactly one input — and the red status LED made it visible at a glance. With a 1.0 ms response at 24 V DC, the registration and synchronization logic closed cleanly, and the conformal coating kept the module reliable in a cabinet near the wash-down area. The builder now keeps a tested 1738-IB8M8 on the critical-spare list and is planning the migration to the 1738-IB8M23 during the next scheduled revamp.
Parameter
| Main Parameters | Value / Description |
|---|---|
| Product Model | 1738-IB8M8 |
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Product Category | Digital Input I/O Module, 8 inputs (ArmorPoint family) |
| Input Type | 8 sink inputs, 8 electronic fusible I/O connections |
| Input Voltage Range | 8 … 132 V AC/DC (120 V AC nominal) — one module covers both DC sensor and AC device wiring |
| Input Current | 9 mA @ 24 V DC (12 mA maximum) |
| ON-State Voltage | 40 … 264 V |
| OFF-State Voltage | 0 … 20 V |
| OFF-State Leakage | 60 V DC maximum |
| Input Words | 4 |
| Response Time, 120 V AC | OFF→ON 5.4 ms; ON→OFF 6.9 ms |
| Response Time, 24 V DC | OFF→ON 1.0 ms; ON→OFF 1.1 ms — fast enough for synchronization loops |
| Response Time, 12 V DC | OFF→ON 1.3 ms; ON→OFF 1.7 ms |
| Isolation, Input to Backplane | 3 kV AC — blocks surges and ground-potential differences from reaching the rack |
| Terminal Fusing | 1.5 A fuse per terminal |
| Internal Fusing | 10 A per group |
| Power Dissipation | 1.1 W |
| Backplane Supply | 24 V DC, 350 mA |
| Module Height | 62.8 mm |
| Weight | 125 g (4.4 oz) |
| Protection | IP20 (DIN-rail or panel mounted) |
| Environmental Coating | Conformal coating — resists humidity and corrosive atmospheres |
| Operating Temperature | -20 … +60 °C (-4 … +140 °F) |
| Storage Temperature | -40 … +85 °C (-40 … +185 °F) |
| Shock / Vibration | Not specified (conformal coating does not imply a mechanical rating) |
| Hazardous Location | T4A, T4B; Ex ec IIC T4 Gc |
| Standards | UL 508; CSA C22.2 No. 213 |
| Certifications | CE, C-Tick, GOST, FM, ATEX / IECEx |
| Mounting | DIN rail or panel |
| Lifecycle Status | Discontinued 30 Nov 2021; documented replacement 1738-IB8M23 |
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