Is Your ControlLogix System Missing the Right Chassis?
Building or expanding a ControlLogix platform often stalls when the chassis is not on hand. The Allen-Bradley 1756-A7 solves that problem. It is a seven-slot chassis that provides the physical connections between modules and the ControlLogix backplane.
This chassis belongs to the ControlLogix series and carries the Allen-Bradley / Rockwell Automation name. It mounts horizontally on a panel and uses four mounting tabs. With an open enclosure, it gives technicians clear access during installation and service.
Technical Specifications That Matter
| Specification | Value |
|---|---|
| Slots | Seven (7) |
| Mounting | Panel mount, horizontal |
| Mounting tabs | Four (4) |
| Backplane current @ 1.2 VDC | 1.5 A |
| Backplane current @ 3.3 VDC | 4 A / 4 A |
| Backplane current @ 5.1 VDC | 15 A / 6 A |
| Backplane current @ 24 VDC | 2.8 A / 2.8 A |
| Power dissipation, max | 4.5 W |
| Dimensions | 50.8 x 60.9 x 20.3 cm (20 x 24 x 8 in.) |
| Weight | 1.1 kg (2.4 lb) |
| Operating temperature, Series B | 0°C to +60°C (+32°F to +140°F) |
| Operating temperature, Series C | -25°C to +60°C (-13°F to +140°F) |
| Storage temperature | -40°C to +85°C (-40°F to +185°F) |
| Enclosure | Open |
The 1756-A7 also hosts a mounting slot for the power supply at the leftmost side. It supports slim, standard, and power supplies. The backplane current ratings show how much power the chassis can distribute to installed modules. At 5.1 VDC, for example, the chassis supplies 15 A total and 6 A per slot. That headroom matters when you populate all seven slots with I/O, communication, or controller modules.
Power dissipation tops out at 4.5 W. The chassis weighs only 2.4 pounds, so one technician can handle it during panel assembly. The minimum cabinet size is 50.8 x 60.9 x 20.3 cm (20 x 24 x 8 in.).
Where the 1756-A7 Fits
Oil and gas operations often need compact control platforms. This seven-slot chassis fits skids, remote wellhead panels, and small process cabinets. Its horizontal orientation saves vertical space inside enclosures.
Industrial automation builders use the 1756-A7 when they need a ControlLogix backplane without a large footprint. It works well in panel shops that assemble systems for packaging, water treatment, and material handling.
Because the chassis supports multiple power supply types, you can match the supply to your load. That flexibility helps when a project grows and you need more modules than originally planned.
Installation and Grounding Notes
Mount the chassis directly to the enclosure subpanel using the four mounting tabs. The 1756-A7 can be installed with or without two SEM screws, but follow your panel design and the manufacturer’s instructions.
The chassis provides functional earth ground and protective earth ground terminals. For the functional earth, use 8.3 sq. mm (8 AWG) solid or stranded copper wire rated at 90°C (194°F) or higher. For the protective earth terminal, use 2.1 sq. mm (14 AWG) solid or stranded copper wire rated at 90°C (194°F) or higher.
Keep the cabinet within the operating temperature range. Series B units run from 0°C to +60°C (+32°F to +140°F). Series C units run from -25°C to +60°C (-13°F to +140°F). Storage range is -40°C to +85°C (-40°F to +185°F).
Maintenance and Reliability
Inspect the chassis periodically for loose modules, dust buildup, and secure mounting. Check that the earth ground connections remain tight. High-vibration areas deserve extra attention because shock ratings differ between operating and non-operating states.
Keep the enclosure free of condensing humidity. The chassis is rated for 5 to 95% relative humidity, non-condensing. In hot climates, verify airflow around the panel so the 4.5 W dissipation does not raise internal temperatures beyond the operating range.
Compatibility and Selection
The 1756-A7 is part of the ControlLogix platform. It accepts ControlLogix modules and supports slim, standard, and power supplies in the leftmost slot. Before ordering, confirm your module count, power budget, and panel dimensions.
If you are replacing an existing chassis, check the series letter because operating temperature ranges differ. Verify current lifecycle status and availability with Oil AutoTech before ordering. For fast dispatch, worldwide, contact Oil AutoTech today for pricing and availability.
