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Allen Bradley 1791 Block I/O 1791-8AC

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1791-8AC

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The Allen-Bradley 1791-8AC is a block I/O module. This module has Eight (8) 120VAC input channels and Eight (8) 120VAC output channels. This module comes with a power supply, PLC interface, I/O connections and signal processing and conditioning circuitry. This device is ideally used for implementation of Remote I/O architecture.

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Rockwell Disclaimer: The product is used surplus. DO Supply is not an authorized surplus dealer or affiliate for the Manufacturer of this product. The product may have older date codes or be an older series than that available direct from the factory or authorized dealers. Because DO Supply is not an authorized distributor of this product, the Original Manufacturer's warranty does not apply. While many Allen-Bradley PLC products will have firmware already installed, DO Supply makes no representation as to whether a PLC product will or will not have firmware and, if it does have firmware, whether the firmware is the revision level that you need for your application. DO Supply also makes no representations as to your ability or right to download or otherwise obtain firmware for the product from Rockwell, its distributors, or any other source. DO Supply also makes no representations as to your right to install any such firmware on the product. DO Supply will not obtain or supply firmware on your behalf. It is your obligation to comply with the terms of any End-User License Agreement or similar document related to obtaining or installing firmware.

Technical specifications for 1791-8AC

ManufacturerAllen Bradley
Product TypeBlock I/O
Product Line1791 Block I/O
Part Number1791-8AC
UPC612598127061
Weight0.94 lbs (0.43 kg)
Output Voltage Range20-123VAC
No. of InputsEight (8)
No. of Groups1 group of 8
On-state Voltage range79-132VAC
No of outputsEight (8
External Power, Voltage85-132VAC
External Power, Current150 mA
MountingVertical / Horizontal
Power Dissipation, maximum12.9 Watts
Thermal Dissipation, maximum43.99 BTU/Hr
Voltage120 Volts AC
Inputs per Block8
Input On-state Voltage Range79 to 132 Volts AC
Input On-state Current5mA at 79 Volts min.
Input Off-state Voltage35 Volts max.
Input Off-state Current2.3 mA min.
Outputs per Block8
External Power85 to 132 Volts AC
Product Lifecycle Status*Discontinued/Obsolete

* The Allen Bradley 1791-8AC has been discontinued by the manufacturer, however we specialize in obsolete parts and can likely still supply surplus and/or refurbished replacement 1791-8AC units instead of migration.

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The 1791-8AC is a Distributed I/O device that is primarily used for implementing Distributed I/O solution. This device supports Allen-Bradley’s RIO protocol, a 3-Wire Protocol utilizing Belden 9463 (or approved equal) cable, connecting RIO such as I/O block modules in daisy chain topology. This module belongs to the legacy I/O block family that is compatibly used with PLC2, PLC3, PLC5 legacy controller platforms as well as RIO enabled SLC500 processors with 1747-SN Remote I/O scanner module.

The 1791-8AC functions as RIO adapter only. It is used to interface up to Eight (8) 120VAC input and Eight (8) 120VAC outputs. It sends input updates to the processor connected in the RIO network and receives control command to actuate the module’s output channels via the same RIO network. The module’s embedded RIO interface allows for seamless integration to the said network.

BTR and BTW sends up to 32 arrays of Read and Write messages, which can be connected in parallel for sending larger amount of messages.

The 1791-8AC also has Eight (8) 120VAC Discrete input channels, with ON voltage range of 85-132VAC. This power supply energizes the entirety of the 1791-8AC and the local backplane, to enable the module perform its locally configured functionality.

The 1791-8AC has 8 outputs with a voltage rating between 20 and 132 Volts AC, and an output current rating of 300 to 600 mA at 30 to 60 degrees Celsius vertical mounting and one of 150 to 300 mA at 30 to 60 degrees Celsius, horizontal mounting. The 1791-8AC’s surge current is 10 Amps for 50 milliseconds recurring every 2 seconds at a minimum ON-state output current of 50 mA per output. It has a maximum drop voltage of 1.5 Volts at 300 mA and an OFF-state current leakage at 3 milliamps. It has an output signal delay time of 1 mA at 60 Hertz OFF to ON and 8.3 milliseconds ON to OFF. The 1791-8AC has a power dissipation of 12.9 Watts and a thermal dissipation of 43.99 BTU/hour. Its isolation voltage of 500 Volts AC is tested at 1250 Volts AC between I/O group-to-group, and I/O group-to-logic. It weighs approximately 0.533 kg. (1.18 pounds) and measures 176.5 millimeters x 68.8 millimeters x 98 millimeters (6.95 inches x 2.7 inches x 3.85 inches).

Revision Part #Also known as
1791-8AC Ser A1791-8AC/A, Series A, Rev A
1791-8AC Ser B1791-8AC/B, Series B, Rev B
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