MicroLogix 1500 System

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System Overview

Product Design

The MicroLogix 1500 system is designed for ease of installation and maintenance. The base units and Compact I/O modules include finger-safe terminal blocks, and both can be either DIN-rail or panel mounted. The base unit or any I/O module can be removed and installed individually, or the entire system can be removed or installed as a unit.

Two MicroLogix 1500 processor modules are available. The standard processor (1764-LSP) provides up to 7.65K words of configurable user memory with a maximum user data space size of 4K words. The enhanced processor (1764-LRP) provides up to 14K words of configurable user memory with a maximum user data space size of 4K words.

You can create long-integer data files (32-bit signed integer, ± 2 billion) for use with math and embedded high-speed I/O instructions. You can also create floating point data files, each of which can contain up to 256 IEEE-754 floating point data elements.

The MicroLogix 1500 processes a typical 1K-word user program (including bit, timer, counter, and math instructions) in approximately 1ms, and it includes built-in resources to facilitate application development:

• Built-in and Modular I/O—The base unit has 24 or 28 built-in I/O. You can add up to 16 I/O modules to support hundreds of I/O points, depending on your power requirements (new 32-point modules available).
  
• Selectable Timed Interrupt—The selectable timed interrupt (STI) provides a mechanism to solve time-critical control requirements in, for example, PID or motion applications. The STI is a trigger mechanism that lets the controller interrupt the program on a user-defined basis to gather time-sensitive data or initiate outputs.
  
• Event Input Interrupts—The MicroLogix 1500 controller supports up to 4 event input interrupts, each of which lets the controller scan a specific program file (subroutine) when an input condition is detected from a sensor. These four input interrupts are assignable to any of the eight high-speed inputs. Eight latching or pulse catch inputs allow very brief signals to be captured and held for input processing.
  
• High-Speed Counters—The MicroLogix 1500 controller (using the 1764-24BWA or -28BXB base unit) includes two built-in independent high-speed counters operating at up to 20kHz, using 32-bit integers for extended range. The high-speed counter instructions support asynchronous control of outputs.
  
• Programmable Limit Switch Function—The Programmable Limit Switch function allows you to configure the high-speed counter to operate as a programmable limit switch or rotary cam switch.
  
• Pulse Train and Pulse Width Modulation Outputs—The MicroLogix 1500 controller (using the 1764-28BXB base unit) includes two outputs each of which can be configured as either a high-speed pulse train output (PTO) operating at up to 20kHz or a high-speed pulse width modulated (PWM) output. Trapezoidal and S Curve profiles on PTO outputs allow user-controlled acceleration and deceleration. Both instructions use 32-bit integers for extended range.
  
• Trim Potentiometers—Two built-in 3/4-turn analog trim potentiometers with a digital output (range from 0 to 250) allow quick and easy adjustments of timers, counters, set points, and more.