Introduction
Plant floors rarely evolve in a straight line. A line commissioned years ago suddenly needs more I/O, a new processor, or a specialty module that did not exist when the cabinet was built. That is exactly where the Allen-Bradley 1756-A17 earns its place. This 17-slot ControlLogix chassis from Allen-Bradley / Rockwell Automation gives you room to grow without ripping out an existing ControlLogix architecture.
The 1756-A17 is a panel-mount chassis that houses ControlLogix processors, I/O modules, specialty modules, and Encompass partner modules. It receives power from a ControlLogix power supply and distributes that power across the backplane, which also acts as a high-speed communication path between every installed module.
Technical Specifications
Key Parameters
| Specification | Value |
|---|---|
| Number of slots | 17 |
| Mounting | Panel mount, horizontal orientation |
| Mounting tabs | 10 |
| Backplane current @ 1.2V DC | 1.5 A / 1.5 A (chassis/slot max) |
| Backplane current @ 3.3V DC | 4 A / 4 A |
| Backplane current @ 5.1V DC | 15 A / 6 A |
| Backplane current @ 24V DC | 2.8 A / 2.8 A |
| Power consumption | 1.8 W |
| Power dissipation | 6.1 BTU/hr |
| Dimensions (WxHxD) | 738 x 169 x 145 mm (29.06 x 6.65 x 5.71 in.) |
| Minimum cabinet size | 914 x 762 x 203 mm (36 x 30 x 8 in.) |
| Weight | 2.20 kg (4.8 lb) |
| Operating temperature, Series B | 0°C to +60°C (+32°F to +140°F) |
| Operating temperature, Series C | -25…+60 °C (-13…+140 °F) |
| Storage temperature | -40°C to +85°C (-40°F to +185°F) |
| Relative humidity | 5 to 95% (without condensation) |
What These Numbers Mean on the Floor
The 5.1V DC backplane rail carries up to 15 A across the chassis, with 6 A available per slot. That headroom matters when you populate the 1756-A17 with a mix of analog, digital, and specialty modules. The 24V DC rail supports 2.8 A per slot, which covers field-side devices that draw from the backplane.
Power consumption sits at just 1.8 W, and heat generation is limited to 6.1 BTU/hr. In a crowded cabinet, that low thermal load keeps surrounding electronics cooler and simplifies ventilation planning.
Compatibility and Integration
The 1756-A17 works with ControlLogix power supplies including 1756-PA72, 1756-PB72, 1756-PA75, 1756-PB75, 1756-PC75, and 1756-PH75. Empty slots require 1756-N2 slot filler modules to maintain proper airflow and backplane integrity.
Field-side wiring connects through a Bulletin 1492 wiring IFM or an RTB. The chassis also supports RIUP (Removal and Insertion Under Power) for easier maintenance, electronic keying to prevent module replacement errors, and built-in time-stamping for Sequence of Events applications.
Because the backplane handles high-speed communication between modules, plan your network layout carefully. Wiring into a ControlLogix network may require an external gateway or connection module. Confirm cables and gateways with your supplier before commissioning.
Installation and Maintenance
Horizontal mounting is the only supported orientation. The ten mounting tabs allow direct panel mounting to the enclosure subpanel. When placing the 1756-A17 near other ControlLogix chassis, maintain the specified clearances: 10.2 cm (4.0 in.) plus power supply width on the left, 7.7 cm (3.0 in.) plus power supply width on the right, 15.3 cm (6.0 in.) on top, and 5.1 cm (2.0 in.) on the bottom.
For grounding, use 8.3 mm² (8 AWG) solid or stranded copper wire rated at 90 °C or greater for functional earth, and 2.1 mm² (14 AWG) copper wire rated at 90 °C or greater for protective earth.
Inspect the chassis periodically for dust buildup and secure mounting. Follow the manufacturer’s safety manual for all maintenance procedures. Do not disassemble or repair internal components.
Selection Guide
Before ordering, verify your power supply model, the number of modules you plan to install, and your cabinet dimensions. The 1756-A17 is available in Series A, B, and C revisions. Series C offers improved slot guidelines, ventilation, tougher mounting tabs, extra mounting tab holes, and an additional ground screw for panel grounding.
Please verify current lifecycle status and availability with Oil AutoTech before ordering. Contact Oil AutoTech today for pricing and availability.
