1771-ASB

The Allen-Bradley 1771-ASB is a PLC 5 Universal Remote I/O Adapter Module. It interfaces with I/O modules in a 1771 I/O chassis with a Remote I/O scanner port for a processor over an I/O link. Using it instead of direct wiring reduces startup, installation, and maintenance costs by the I/O being closer to the actuators and sensors. It is compatible with 32 I/O-adapter devices via the I/O link and it uses 82 Ohm or 150 Ohm terminating resistor.

The 1771-ASB module has a communication rate of 57.6 Kbps, 115 Kbps, and 230 Kbps and it weighs 1.9 pounds. It has a backplane current load of 1 A at 5 Volts DC and a maximum power dissipation of 5.2W. It requires a remote I/O adapter port for connection. For installation, it must be mounted in the left-most slot of the 1771 chassis with the I/O modules controlled by a PLC 5 processor. For wiring, the 1770-CD Belden 9463 or equivalent cable must be used. The 1771-ASB module has Active, Adapter Fault, and I/O Rack fault diagnostic Indicators, 2 switch assemblies, and a field wiring arm. It provides faster data transmission and backplane scanning up to 2500 feet at 230.4K Baud. It supports serial communication and reads/writes data in parallel form. It supports 4, 8, 12, 16, or 32-slot I/O chassis and 1 and 2-slot I/O addressing. The 1771-ASB improves scan time and I/O image space savings by scanning all slots except the last 4. It eases troubleshooting with its enhanced diagnostics features.

The 1771-ASB is an Allen-Bradley hardware that belongs to the PLC 5 product family of Programmable Logic Controllers (PLC). This electronic hardware is a remote I/O adapter that is used to interface the to Remote I/O (RIO) network. In actual, this RIO adapter responds to the request of the Remote I/O (RIO) scanner in the network. This adapter supports transmission of data at cable length and speeds of 10,000 feet at 57.6K baud, faster backplane scanning and data transmission up 2500 feet at 230.4K baud.

RIO Communication is physically implemented following daisy-chain topology. In this topology, the start and end points must be installed with a terminating resistor to close the network segment. The same is true for this protocol, either an 82 Ohm or 150 Ohm resistor may be used to terminate the segment. 150 Ohm is used for older configuration while 82 Ohms is used in enhanced RIO network versions. Belden 9463 or more popularly known as Belden Blue Hose cable is used for Remote I/O protocol.

This module is provided with status indicators such as ACTIVE, ADAPTER FAULT, and I/O RACK FAULT. For the Active status, the LED light should be Green to indicate normal operation. When an adapter fault is experienced, Red light illuminates while for Rack Fault, RED led activates.

This module receives/sends data from/to the I/O scanner in serial form, reads/writes data from/to the input modules in parallel form, reads/writes data from/to the output modules in parallel form.