1791 Block I/O Repair

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The 1791 block I/O module series by Allen-Bradley is a series of compact, stand-alone, and remote I/O devices with built-in power supplies, programmable controller interfaces, input/output points, and signal conditioning circuitry for complete system control. These modules are compatible with the Allen-Bradley PLC (2, 3, and 5) controllers and the SLC-500 modular controllers, and they are connected either directly to the controllers in the PLC-3 and PLC-5 programmable controller family or they are connected by using compatible scanner modules. The 1791 block I/O modules have DC power requirements with an operating voltage range between 10 and 30 Volts DC, and they require 200 milliamps of current and a 5.5 Amps (for 10 milliseconds) inrush current to power each block. This series features modules with sinking and sourcing inputs and outputs ranging from 8 to 64 connections, and they have removable remote I/O links, input/output connectors, and terminals for external 24 Volts DC power supply that help reduce wiring costs.

The 1791 block I/O modules have dual DIP switches for setting the I/O configurations and addressing rack numbers. These switches also let the users select and adjust the transmission rates, initiate last racks and I/O groups, and select the last state and DH–485 terminator. A DH-485 port is provided in all modules for connecting to SLC controllers, and this network (DH-485) offers a maximum network communication distance of 4,000 feet. A bi-color LED indicator is also provided on every module for providing power, active, communication, and fuse blown statuses. Depending on the application requirements, multiple I/O blocks can be wired in series via the removable connectors, and a termination resistor must be wired on both ends of the wiring series. The 1791 block I/O modules can provide a maximum network distance range of 2000 to 10,000 cable-feet, and an adjustable baud rate from 57.6 Kilo-baud to 230.4 Kilo-baud.