The AB 1771-A3B1 is an I/O chassis for 1771 I/O modules. The 1771 PLC-5 system is a modular system that needs a 1771 I/O chassis to allow the installation of various modules. Communication between the I/O modules and either the processor module or the I/O adapter module is provided by the backplane. The 1771-A3B1 chassis has 12 I/O slots. It has dimensions of 12.4 x 19.0 x 7.6 in. and weighs 12.6 lbs. For installation in a 1771 PLC-5 system, it uses a back-panel mounting method with adequate spacing and open enclosure. The chassis backplane has a power supply of 8A at 5V DC. The 1771-A3B1 chassis has a universal configuration for chassis mounting and system design because of its own consistent design. For future expansion, it can be easily replaced with a larger chassis. It is intended for use in an industrial environment with a 0 – 60 °C (32 – 140 °F) operating temperature, 5-95 % noncondensing relative humidity, and a 30g operating shock.

The AB 1771-A3B1 is a universal I/O chassis that is part of the 1771 Product bulletin. This module is mainly used to provide an installation location of Programmable Logic Control (PLC) hardware such as Power Supplies, Processors, I/O modules, and specialty modules. It also provides the hinge of various wiring arms which are used to terminate signal wires for interfacing to modules.

The 1771-A3B1 hosts the module connectivity to the backplane as well as the backplane itself. Output voltage and current of the connected power supply is distributed by electronic circuitry installed to this chassis which is received by each installed module. This chassis can accommodate up to twelve (12) modules and may be used as local, extended, or Remote I/O (RIO) rack. It has a maximum output current of 24 Amperes and supports panel mounting only via the provided mounting tabs. This chassis is secured to the enclosure back panel with the use of ¼-20 (M6 x 10) mounting bolts.

This chassis has temperature specifications of 0 to 60 degrees Celsius or 32 to 140 degrees Fahrenheit for operating temperature and a storage temperature of -40 to 85 degrees Celsius or -40 to 185 degrees Fahrenheit with a relative humidity of 5 – 95%, non-condensing. It weighs 5.9 kilograms or 13 pounds and physically measures 483 x 339 x 221 millimeters or 19.0 x 12.4 7.6 inches. It is approved and certified for use in Class 1, Division 2, Groups A, B, C and D application areas with operating shock and vibration of 2g at 10-500 Hertz and 15g, respectively.