MicroLogix 1100 Selection Guide

Allen-Bradley’s MicroLogix line of Programmable Logic Controllers offers a fantastic value for small-scale automation projects. Where you might not need large I/O counts but could benefit from advanced process control and communication solutions such as those found in industrial machine applications, MicroLogix PLCs have you covered. The MicroLogix 1100 model is the current entry-point into the MicroLogix family, packed with control and integration technology pulled from larger platforms, consolidated into a cost-effective, small footprint package. In this article, we’ll review the MicroLogix 1100’s technical details, compare model selections, and provide a few application suggestions.

MicroLogix Family Overview

Allen-Bradley’s PLC offerings are extensive, scaling from tiny ‘smart relay’ jobs to multi-site SCADA applications. The MicroLogix family of PLCs sits towards the smaller-scale end of their product line, just below the midline CompactLogix and flagship ControlLogix platforms but above the Micro platform. These platform tiers are certainly not separated by quality or reliability – AB’s tiers only serve to describe the general application size and complexity that each PLC family is designed to best help. The MicroLogix family is particularly well-positioned to handle single-machine control functionality that can benefit from advanced communication, IO, recipe batching, PID control, small form factor, and human interface options.

There are two aspects that define the Allen-Bradley MicroLogix family of PLCs: compact size and cost-effective modern process control. Below is a breakdown of the five-product series in the family.

With the introduction of the newer Micro PLC family, Allen-Bradley has discontinued the older MicroLogix 1000 and MicroLogix 1500 series, leaving the MicroLogix 1100 as the entry point into the family. As a result, the 1100, 1200, and 1400 are the remaining available new models as of the date of this article.

In general, the MicroLogix family is centered around offering a single-device solution to small machine applications, containing a mix of embedded IO points and communication ports on the PLC itself. Often, all you’ll need for small applications is the PLC base unit alone. However, when additional IO or communication options are required, the MicroLogix family shares expansion modules between series, allowing for expanding your PLC platform for larger projects.

Please note that Allen Bradley uses Bulletin numbers to categorize their product lines. The MicroLogix 1100 series, for instance, has a Bulletin number of 1763. In turn, this bulletin number becomes the prefix for all part numbers used when specifying and ordering parts specific to the 1100 series.

Some components are shared across the MicroLogix series to make matters a little more complicated, so extra attention is needed when searching for compatible components. For example, the MicroLogix 1100 and 1200 series share add-on expansion IO modules – a 1763-L16BBB MicroLogix 1100 PLC can add an 8-point relay output module with a part number 1792-OW8. Further on, you might add a communication cable to your 1100 with a part number of 1761-CBL-AM00, where the 1761 bulletin number corresponds to the MicroLogix 1000 series. We suggest that you obtain and read your MicroLogix series’ specific User Manual document to confirm the compatibility of accessories and components before purchase.

MicroLogix 1100 Overview

The MicroLogix 1100 series consists of (4) models that vary in I/O, power supply voltages, and exceptional motion control capabilities. Common to all models are integrated communication options, advanced PID control, online editing, and even an embedded LCD screen for local interaction and data display.

Across the MicroLogix 1100 controller series, the following common features include:

• 10 digital inputs
• 6 digital outputs
• 2 analog inputs
• Expandable up to four 1762 I/O modules for up to 144 digital I/O points
• Expandable communication options with 1761 Serial, Ethernet, or DeviceNet interfaces
• Programmable with RSLogix 500 or RSLogix Micro software
• True online editing
• 4k word user program memory
• 4k word user data memory
• Up to 128k bytes for data logging and 64k bytes for recipe storage (recipe storage subtracted from data logging storage)
• One RS-232 / RS-485 combo serial port with DF1/DH485/Modbus RTU/ASCII protocols
• One Ethernet port supporting Ethernet/IP protocol
• Embedded Web Server
• Onboard LCD screen

We find the MicroLogix 1100 controller to fit quite nicely into the small machine or system applications where IO and communication demands are relatively small. Still, robust programming and control features would prove valuable. Online editing with the MicroLogix family is very beneficial, especially in tuning and troubleshooting PID loops, frequency operations, and batch sequences live. Where minor human interaction may be valuable but short of justifying an HMI, the onboard LCD screen allows for real-time data/condition monitoring, I/O status, option toggles to interact with the control program, and even to serve as trim pots for precise point tuning, right on the PLC chassis and without the use of a laptop.

Expansion module options grant us more advanced capabilities for most any industrial process – selections span multi-channel analog and discreet I/O, RTD/resistance inputs, thermocouple/mV inputs, and a host of communication protocols including serial, DeviceNet, EtherNet/IP, and EtherNet/IP with Web Server functionality.

Standard MicroLogix 1100 Models

The below table shows (4) catalog number models available in the MicroLogix 1100 PLC series. These models differ by supply power and I/O types. All chassis enclosures are physically the same between models, with only I/O assignments being different internally. Note that the I/O selections listed below are all embedded into each chassis, and additional capacity can be achieved using expansion modules regardless of the selected base unit.

The Allen-Bradley document ‘MicroLogix Programmable Controllers Selection Guide,’ publication #1761-SG001D-EN-P, offers additional detail into making the proper selection for your MicroLogix 1100 (and other) PLCs. The two tools above exhibit our options within the 1100 series. In effect, our limited few choices are (3) functional areas, with (2)-(3) choices each. We have three selections for input type (120V AC, 24V DC, or 12-24V DC), two selections for output type (Relay/24V DC or Relay), and three selections for power supply type (120/240V AC, 24V DC, or 12-24V DC).

You’ll want to look back at the product specifications and catalog options to know which combinations of selections are possible. The matrix above is not meant to suggest that any combinations of choices can be supplied. For example, you cannot select an “…L16DBA”, which would call for 120V power supply but 12-24V DC I/O.

We’ll remind here again that the MicroLogix 1100 PLC has a Bulletin number of 1763 but works with expansion modules under Bulletin 1762, communication interfaces under Bulletin 1761, cables under Bulletin 1761, and the expansion memory module under Bulletin 1763.

Application Considerations

As with the other series in the MicroLogix family, our selection options for the 1100 series are pretty pre-defined for us. Functional, programmatic, and interface types are all standardized across the available catalog numbers, so our selection criteria for choosing a model to purchase is essentially around power and I/O types. Of the two, I/O selection would be the element warranting the most attention. Below we’ll present a table that shows I/O options by catalog number with more clarity, as pulled from the MicroLogix above Programmable Controllers Selection Guide document.

Have a standard relay control, stop-start type application? The base catalog model 1763-L16AWA will likely be sufficient.

Adding instrument inputs for online process or condition monitoring, such as via pressure or temperature sensor? You’ll get that functionality with an option, as all models have (2) analog inputs onboard.

Adding even more complex process conditions, such as a high-speed counter input? Any of the 1763-L16BWA, …BBB, or …DWD would work well, depending on the input voltage.

Adding an analog output to the mix? You can select any base model and add an expansion module for analog outputs, such as the 4-channel 1762-IF4.

If you would like the added security of having onboard program backups, add a 1763-MM1 memory module. This memory module is purely for backups, auto-recovery, and transporting program copies away from the controller. It does not add additional system space to the onboard persistent memory capacity.

The MicroLogix 1100 series truly shines in Remote Terminal Unit (RTU) applications. Small portions of a more extensive process can be decentralized to local PLCs and integrated via communication protocols across a SCADA array. Small process systems, packaging, material handling, small machine or sub-system, remote monitoring, and remote interface control are great examples to consider placing an ML 1100.

Batching and recipe automation that are memory intensive but only need small I/O counts are further excellent examples of applications where a MicroLogix 1100 PLC will offer a cost-effective, robust solution.

We hope this run-through of the MicroLogix 1100 family has been valuable in comprehending your selection options. For more information or to discuss which PLC might be best for your application, please visit our website here, or contact us at [email protected] or 1-800-730-0292.

This entry was posted on July 28th, 2021 and is filed under Allen-Bradley, Automation, Education. Both comments and pings are currently closed.