Allen-Bradley 1771 Analog I/O Modules

1771 I/O Module

The 1771 I/O product line provides a full range of digital and analog I/O for a wide variety of applications in a modular assembly — including intelligent I/O modules.

• Digital I/O modules have digital I/O circuits that interface to on/off sensors such as pushbutton and limit switches; and on/off actuators such as motor starters, pilot lights, and annunciators. The outputs are directly controlled by the state of corresponding bits in the PLC data table, while the inputs directly control the state of corresponding bits in the PLC data table.
• Analog I/O modules perform the required A/D and D/A conversions to directly interface analog signals to PLC data table values using up to 16-bit resolution. Analog I/O can be user-configured for the desired fault-response state in the event that I/O communication is disrupted. This feature provides a safe reaction/response in case of a fault, limits the extent of faults, and provides a predictable fault response.
• N-series Analog I/O modules provide high (1000V) isolation between channels. Their I/O connection points are on Remote Termination Panels (RTPs) which reduce installation costs and allows replacement without disturbing current loop. RTPs have optional fuses and resistors for user-defined termination flexibility.
• Specialty I/O modules are available for further control system enhancement. These modules include process control modules, positioning modules, and specialized modules such as the high-speed logic controller module and the configurable flowmeter module. Each provides a unique easy-to-use interface between the I/O (digital and/or analog) circuits and the PLC processor.
• In a processor-resident local I/O chassis of a PLC-5 controller
• With a 1771-ALX I/O adapter on an Extended Local I/O link with the processor
• At a location remote from the processor, in an I/O chassis with a 1771-ACN15 or -ACNR15 I/O adapter on a ControlNet link with the processor
• At a location remote from the processor, in an I/O chassis with a 1771-ASB I/O adapter on a Universal Remote I/O link with the processor

Benefits

• No need to disconnect wiring to replace module; for some modules, wiring arms are shipped with I/O modules; the others use remote termination panels; for N-series modules, order remote termination panels separately.
• Solid-state outputs are fused for module-circuit protection.
• Modules available in different densities (32 I/O per module max) for greater flexibility and cost savings.
• Isolated inputs and outputs can be used in applications, such as motor control centers where individual control transformers are used.
• 1771 I/O modules include optical coupling and filter circuitry for signal noise reduction.
• For troubleshooting, status indicators are provided on the front of modules to input or output and fuse blown status.
• Digital I/O modules cover electrical ranges from 5…276V AC or DC; relay contact output modules are available for ranges from 0…276V AC or 0…175V DC.
• A range of analog signal levels including standard analog inputs and outputs; and direct thermocouple and RTD temperature inputs.
• Analog module software-selectable features include digital filtering for noisy transmitters and environments and range selection per I/O for added flexibility.
• Analog module comprehensive self-diagnostic tests: over/under range, high/low rate-of-change alarming, open input/open loop detection, on-board error checking.
• Scaling to engineering units makes incoming analog signals easier to work with.
• User-configurable output response (min, max, mid-range or last value) for safe reaction to an analog module fault.
• An analog module status block provides information to the processor for alarming and troubleshooting.
• Current inputs with individual embedded 24V DC loop power for analog transmitters.
• A 1771 intelligent I/O module may perform the function of three modules of a smaller physical size.

Specifications

Analog I/O Modules

1771 N-Series Analog I/O Modules

• • All input channels have scaling, high/low alarms with dead band, rate alarm, and digital filtering.

• • Each 4-channel module requires one cable assembly for connection to its RTP. Each 8-channel module requires two cable assemblies for connection to its RTP. The available cable assemblies are: 1771-NC6 (6 ft) and 1771-NC15 (15 ft).

• • Each modules has a channel update period of 25 ms per module.

• • For each module, the data format is BCD or natural binary.

• • All output channels have scaling, user-defined last state, high/low clamp limits, and rate-of-change alarm.

• • For each module the step response @ 99.9% is 125 ms.

• Each module occupies one slot.