Allen-Bradley PLC Guide: Micro800, CompactLogix and ControlLogix

Allen-Bradley PLC hardware is the programmable logic controller range that Rockwell Automation sells under the Allen-Bradley brand, split into three current controller families: Micro800 for small standalone machines, CompactLogix for mid-range machine control, and ControlLogix for full production lines and large processes. Allen-Bradley launched one of the first programmable controllers in 1970, the 1774 PLC, and today’s Allen-Bradley PLC controller line is programmed in Connected Components Workbench or Studio 5000 Logix Designer, connects to PanelView HMI terminals over EtherNet/IP, and pairs with PowerFlex variable frequency drives.

This guide compares the three families side by side, then covers the MicroLogix 1400 and legacy series, Allen-Bradley PLC programming, Siemens PLC vs Allen-Bradley, PanelView HMI and PowerFlex VFD pairing, and the 1756-BA2 ControlLogix battery.

Allen-Bradley PLC Families and Types at a Glance

A common misconception views Allen-Bradley and Rockwell Automation as separate makers: Allen-Bradley is the brand and Rockwell Automation is the company behind it. As a controller manufacturer, Rockwell describes PLCs and PACs as industrial computers, built around a CPU, memory, and I/O, that automate machinery and processes. It groups its range under the heading “PLC/PAC”: programmable logic controllers (PLCs) for machine-level and discrete control, and programmable automation controllers (PACs) for larger systems that integrate control, motion, and data. The line between the two is a spectrum, not a binary — manufacturers apply the labels by target audience, so judge a controller on I/O capacity, programming environment, and protocol support rather than on its label. Each Allen-Bradley PLC type below runs the same scan-cycle logic — read inputs, execute the program, write outputs — and differs in scale, speed, and built-in functions.

The range has grown in generations. Allen-Bradley moved from the PLC-2, PLC-3, and PLC-5 lines to the SLC 500 in 1991, the MicroLogix in 1994, the ControlLogix in 1997, the CompactLogix in the mid-2000s, and the Micro800 in 2011. Credit for the very first PLC is contested: Foxmere notes that Dick Morley of General Motors and the Modicon 084 are the other claimant. The SLC 500 is the generation that has already closed — Foxmere reports that all remaining SLC 500 controllers were discontinued on 31 March 2024.

Three Allen-Bradley PLC series cover new installations today, and RealPars ranks them by position: Micro800 as the entry-level range, CompactLogix as the mid-range system, and ControlLogix as the flagship. The next three sections take each in turn.

Micro800 — Entry-Level Allen-Bradley PLC Controller

Micro800 is Allen-Bradley’s entry-level PLC family, introduced in 2011 and aimed at small standalone machines. RealPars describes Micro800 controllers as low-cost units with limited functionality, suited to simple applications, and extended with plug-in modules that add I/O, communication options, or extra functions. Rockwell lists pumps, conveyors, and packaging equipment among typical Micro800 applications.

Software is the second reason Micro800 is a common starting point. Connected Components Workbench, the programming software for Micro800, is available to download and use for free, so RealPars recommends the family for learning PLC programming without spending on hardware or software licences.

Rockwell’s controller overview positions Micro800 as a compact option for smaller standalone machines, with flexible I/O, communication capabilities, and easy programming for OEM equipment and basic automation systems. Connected Components Workbench also programs the PanelView 800 graphic terminals, so a small machine can keep its controller and its operator terminal in one software package. Where a Micro800 machine grows, Rockwell’s MicroLogix-to-Micro800 migration guide and the CompactLogix step below give the upgrade path.

The limit is scope. When a machine needs high I/O counts, motion control, many variable frequency drives, or integrated safety, RealPars points to CompactLogix instead. That step up is the mid-range family covered next.

CompactLogix — Mid-Range Allen-Bradley PLC Controller

CompactLogix is Allen-Bradley’s mid-range PLC system, with faster scan times and more configuration options than Micro800, and the ability to control more devices — enough for complex machines and small processes. Rockwell’s controller overview describes CompactLogix as the choice for small to mid-sized applications that need high performance in a compact footprint.

The current generation is the CompactLogix 5380, built on the 5069 hardware series and programmed in Studio 5000 Logix Designer. Rockwell specifies:

• a 1 gigabit (Gb) embedded EtherNet/IP port and dual configurable ports with Dual-IP address support;
• integrated motion over EtherNet/IP for up to 32 axes;
• Compact GuardLogix safety variants reaching SIL 2/PLd with a 1oo1 architecture or SIL 3/PLe with a 1oo2 architecture;
• CIP Security support, available with Studio 5000 Logix Designer version 34 or later;
• process variants (catalog numbers 5069-L320ERP and 5069-L340ERP) tied into the PlantPAx 5.0 system.

Rockwell lists packaging applications — labeling and wrapping, vertical form fill and seal, blistering feeders — and industries including food and beverage, water and wastewater, automotive, and semiconductors and electronics. Owners of older CompactLogix 1769 controllers (1769-L32E, -L32EK, -L35E) and SLC 500 units are pointed to migration support toward selected CompactLogix controllers. Beyond that mid-range ceiling — redundancy, HART, or plant-wide scope — the flagship family below takes over.

ControlLogix — Flagship Allen-Bradley PLC Controller

ControlLogix is the flagship Allen-Bradley PLC, and RealPars places it at the top for full production or packaging lines and large processes. It is rack-based — controllers sit in a 1756 chassis — and, per Foxmere, was released in 1997 with RSLogix 5000 as its original software. Two generations matter for allen-bradley plc controllogix specifications: the 5570 and the 5580.

Rockwell’s 5570 page lists standard, safety, extreme-temperature, and On-Machine models for process, motion, discrete, and high-availability work, with full controller redundancy, Removal and Insertion Under Power (RIUP), and communication over EtherNet/IP, ControlNet, DeviceNet, Data Highway Plus, Remote I/O, and SynchLink. Programming uses relay ladder logic, structured text, function block, and sequential function chart (SFC). Both generations list a maximum of 128,000 digital and 4,000 analog I/O points, and the controllers support as many as 100 axes of integrated motion over EtherNet/IP or Sercos.

The 5580 adds a 1 Gb embedded Ethernet port, an onboard display, security mechanisms such as centralized authentication and access control, and — from Studio 5000 Logix Designer version 33 — redundancy on the same firmware, plus process, extreme-temperature, and no-stored-energy variants. ControlLogix and GuardLogix 5580 controllers cover SIL 2/PLd and SIL 3/PLe safety solutions. RealPars adds that ControlLogix supports functions absent from Micro800 and CompactLogix, including redundancy (the process keeps running if one device faults) and HART communication, common in the process industry. Rockwell’s listed applications run from energy and power generation and dairy food and beverage to mining and metals, pulp and paper, and water and wastewater.

Flextech Industrial lists Allen-Bradley ControlLogix in its PLC Malaysia range alongside the Mitsubishi, Omron, Panasonic, and Xinje ranges.

Summary So Far — Micro800, CompactLogix, and ControlLogix

Micro800, CompactLogix, and ControlLogix split the Allen-Bradley PLC range by scale. Micro800 covers entry-level standalone machines and is programmed in free software. CompactLogix steps up to mid-range machine control, with 1 Gb EtherNet/IP, integrated motion for up to 32 axes, and safety variants. ControlLogix is the flagship for production lines and large processes, with redundancy, up to 100 axes of integrated motion, and a 1756 chassis. All three are Allen-Bradley PLC options; the difference is scale and built-in capability, not brand.

Micro800 vs CompactLogix vs ControlLogix — Which Allen-Bradley PLC Fits

Six factors separate Micro800, CompactLogix, and ControlLogix in practice, and together they decide which Allen-Bradley PLC fits a machine.

The tier row maps each family to the closest of Flextech’s class-level Malaysian price bands; actual price depends on the exact model and I/O configuration.

Reading down the table gives the decision rule. Pick Micro800 when the machine is a standalone unit with modest I/O and the software cost should be zero. Pick CompactLogix when the machine needs many drives, motion axes, or integrated safety. Pick ControlLogix when the line needs redundancy, HART, or a rack that scales across a whole plant. Machines already running the older MicroLogix 1400 sit outside this three-way split, so that controller gets its own section next.

Allen-Bradley PLC Micrologix 1400 and Legacy Series

The Allen-Bradley PLC MicroLogix 1400 belongs to the MicroLogix line, which predates Micro800 and sits beside the older PLC-5 and SLC 500 generations. The line debuted in 1994 with the MicroLogix 1000 as a smaller, cheaper controller that brought most SLC 500 functionality to RSLogix 500 programming, according to PLC Technician. Rockwell’s MicroLogix 1400 (Bulletin 1766) builds on the MicroLogix 1100 with EtherNet/IP, online editing, and a built-in LCD with backlight.

Rockwell’s MicroLogix 1400 specifications include:

• 32 digital I/O points, or 32 digital plus 6 analog I/O points on analog versions;
• up to seven 1762 expansion I/O modules, reaching 256 discrete I/O;
• up to six embedded 100 kHz high-speed counters (only on controllers with DC inputs);
• two serial ports with DF1, DH-485, Modbus RTU, DNP3, and ASCII protocol support, and an Ethernet port with web server, email, and DNP3 support;
• 10 K words of user program memory and 10 K words of user data memory, with up to 128 KB for data logging and 64 KB for recipe storage;
• programming in RSLogix 500.

Typical applications include material handling, packaging, printing, food and beverage, and water and wastewater. Rockwell still publishes MicroLogix 1400 documentation and a MicroLogix-to-Micro800 migration guide (publication 2080-RM002), which is the practical route when a MicroLogix machine is upgraded. On the small end of the range, a Micro800 replaces a MicroLogix; on the large end, CompactLogix and ControlLogix replaced the older SLC 500 and PLC-5 generations. Whichever family a machine uses, the controller only runs once its software project is written, which is where programming starts.

Allen-Bradley PLC Programming — Studio 5000, Connected Components Workbench and RSLogix 500

Allen-Bradley PLC programming depends on the family, and three packages cover them. Studio 5000 Logix Designer programs CompactLogix and ControlLogix and manages the whole Logix 5000 family. Connected Components Workbench programs Micro800. RSLogix 500 programs MicroLogix. RealPars adds that Allen-Bradley software has carried several names over the years — RSLogix 500, RSLogix 5000, and Studio 5000 Logix Designer.

That naming history explains the search phrase “plc allen bradley 5000”, which can point to four different things:

• Logix 5000— the controller family (CompactLogix and ControlLogix);
• Studio 5000— the engineering software environment;
• RSLogix 5000— the earlier name for the same programming software;
• 5000-series hardware— controllers such as the ControlLogix 5570 and 5580 or the CompactLogix 5380.

Studio 5000 is paid software, sold by subscription, while Connected Components Workbench is free to download. Studio 5000 also includes tools such as Studio 5000 Logix Emulate, which validates and tests application code independent of hardware, and Studio 5000 View Designer for PanelView 5000 terminals. The programming languages available on Logix 5000 controllers are ladder diagram, structured text, function block diagram, and sequential function chart.

MRO Electric’s working sequence for a first program includes these steps:

1. Install the software — RSLogix 500 for MicroLogix, Studio 5000 Logix Designer for CompactLogix and ControlLogix — plus RSLinx, the communication software that connects a PC to the PLC. MRO notes that Allen-Bradley offers free trial versions of many packages.
2. Connect the PC by USB, Ethernet, or serial, depending on the model, and configure a communication driver in RSLinx.
3. Create a new project and select the exact processor type, such as a MicroLogix 1400 or a CompactLogix L33ER.
4. Define the I/O modules so they match the physical hardware.
5. Write the logic in ladder — contacts (normally open and normally closed) for inputs, coils for outputs, plus timers and counters.

For the same subject across other brands, see Flextech’s PLC programming software comparison. Software choice is also the sharpest point of difference when Allen-Bradley is set against Siemens, covered next.

Siemens PLC vs Allen-Bradley — Where the Two Differ

Siemens PLC vs Allen-Bradley is a comparison of two three-tier ranges. Allen-Bradley runs Micro800, CompactLogix, and ControlLogix; Siemens runs LOGO!, S7-1200, and S7-1500, all engineered in TIA Portal (see Flextech’s Siemens PLC guide). PLC Technician finds the two evenly matched on speed, reliability, and output, so the differences sit elsewhere.

SimplyBuy Global, a controller supplier, frames the split as maintenance versus engineering: Allen-Bradley is designed around maintenance teams (tag names, live online edits), Siemens around engineers (structured data, one engineering environment). The same source lists higher hardware cost and annual software support fees on the Allen-Bradley side, and recommends Allen-Bradley for North American plants and high-speed discrete work such as packaging and bottling, and Siemens for Europe, Asia, or South America and for process control — opinion, not a standard. PLC Technician draws its installation contrast from Allen-Bradley’s rack-based systems, so it applies most to ControlLogix rather than to compact Micro800 units. The practical rule for a Malaysian plant is to match the controller to the machine’s origin and the maintenance team’s existing software, because a second engineering package is an ongoing licence and training cost either way. Either brand’s controller also needs an operator terminal and a motor drive around it, which the next section covers for Allen-Bradley.

Allen-Bradley HMI and VFD — PanelView and PowerFlex

An Allen-Bradley PLC controller rarely runs a machine alone. Allen-Bradley HMI terminals and PowerFlex drives complete the same automation layer, and both connect to Logix controllers over EtherNet/IP.

PanelView HMI. Rockwell has several HMI lines under the PanelView name, each with its own software. PanelView Plus terminals are programmed in FactoryTalk View Machine Edition and exchange data with the controller, usually over Ethernet. PanelView 5000 is programmed in Studio 5000 View Designer, and PanelView 800 in Connected Components Workbench. RealPars describes the PanelView Plus 7 Performance as the premium model for large, complex applications (up to 300 displays and 400 alarms) and the PanelView Plus 7 Standard as the mid-range model for smaller applications (up to 25 displays and 200 alarms); a PanelView Plus 6 generation also remains listed. Rockwell also lists graphic terminals, tethered operator terminals, and FactoryTalk Optix as visualization options.

PowerFlex VFD. The Allen-Bradley VFD line is PowerFlex, with power ranges that Rockwell states as:

• compact drives up to 22 kW (30 Hp);
• mid-range drives for fans, pumps, compressors, blowers, and conveyors up to 270 kW (400 Hp);
• high-performance drives up to 4500 kW (6000 Hp);
• medium-voltage PowerFlex 6000T and 7000 drives.

Rockwell states that, in cases where a PowerFlex drive is integrated with a Logix controller, both are configured in a single development environment and Automatic Device Configuration simplifies maintenance and reduces downtime.

For Malaysian system integrators sourcing the surrounding parts, Flextech Industrial’s HMI Malaysia category carries Delta and Xinje panels, and its inverter Malaysia category covers drives from Mitsubishi, Panasonic, Siemens, Toshiba, Xinje, and NAIS. Flextech is not an authorized distributor for these brands; parts are sourced directly from manufacturers and reputable international agents, with local warranty coverage on items sourced internationally. To match a controller to an existing line, get a quote from Flextech’s team. One maintenance part on older ControlLogix systems sits outside the HMI and drive layer — the controller’s backup battery, covered next.

ControlLogix Battery 1756-BA2 — What to Know Before Replacing

The 1756-BA2 is a lithium battery assembly for older ControlLogix controllers. Rockwell’s product page describes it as the “ControlLogix L6X Ser B ONLY Battery Assy”, for use with Series B 1756-L6x controllers, and lists it for use with the ControlLogix 5560 and with a 0–60 °C (32–140 °F) temperature rating.

Points to check when planning a replacement include:

• Rockwell lists the 1756-BA2 as End of Life, with a discontinued date of 31 December 2027 and no planned Rockwell replacement, so stock for older L6x controllers should be planned early.
• Rockwell’s older ControlLogix battery documentation is part-specific: publication 1756-IN576 covers the separate 1756-BATM battery module and limits it to particular controllers (1756-L55Mxx, -L61, -L62, -L63), and it is not a 1756-BA2 manual. A newer controller may use a different energy-storage part — Rockwell’s ControlLogix 5580 comparison table lists an Energy Storage Module (ESM) as a feature — so identify the controller series from its label and read the manual for that exact part before ordering.
• A PLCtalk forum thread on the 1756-BA1 and 1756-BA2 notes that the BA2 has charge control and status electronics built in, unlike the earlier BA1.

Third-party replacement cells for the 1756-BA2 are also listed in Malaysia and abroad, described as 3.0 V, 1200 mAh, non-rechargeable lithium. Rockwell’s own page carries an authenticity note asking buyers to register the product, so confirm the source and the part number against the controller series before fitting any battery. Battery status, like family choice and software, comes down to matching the exact controller series, and the questions below restate the key points briefly.

ControlLogix Battery 1756-BA2 — What to Know Before Replacing

Frequently Asked Questions

Frequently asked questions about Allen-Bradley PLC families, programming software, and spares cover what engineers and buyers ask most once the three controller families are understood.

What is an Allen-Bradley PLC controller?

An Allen-Bradley PLC controller is a programmable logic controller made by Rockwell Automation under the Allen-Bradley brand. It reads inputs from sensors and switches, runs a stored program, and drives outputs such as motors and valves, and it comes in three current families: Micro800, CompactLogix, and ControlLogix.

What are the main Allen-Bradley PLC types?

The main Allen-Bradley PLC types are Micro800 (entry-level, small standalone machines), CompactLogix (mid-range, complex machines and small processes), and ControlLogix (flagship, full production lines and large processes). Older series include the PLC-5, SLC 500, and MicroLogix, and the SLC 500 was discontinued on 31 March 2024.

Is the MicroLogix 1400 still supported?

Rockwell still publishes MicroLogix 1400 product pages, manuals, and a MicroLogix-to-Micro800 migration guide. The MicroLogix 1400 is programmed in RSLogix 500, and Micro800 with Connected Components Workbench is the small-machine family that Rockwell’s migration guide points to.

What software programs an Allen-Bradley PLC?

The software that programs an Allen-Bradley PLC depends on the family: Studio 5000 Logix Designer for CompactLogix and ControlLogix, Connected Components Workbench for Micro800, and RSLogix 500 for MicroLogix. Connected Components Workbench is free to download; Studio 5000 is paid, subscription-based software.

Is Siemens or Allen-Bradley better?

Siemens or Allen-Bradley is better only in cases where the application and the maintenance team’s software favour one; neither wins on performance alone. PLC Technician rates them evenly on speed and reliability; Allen-Bradley is regarded as more user-friendly and is far more popular in North America, while Siemens is regarded as easier to install and far more popular in Europe. The deciding factor is usually the engineering software the maintenance team already uses.

What battery does a ControlLogix PLC use?

Older Series B 1756-L6x ControlLogix controllers use the 1756-BA2 lithium battery, which Rockwell lists as End of Life with a 31 December 2027 discontinued date. Newer controllers may use an Energy Storage Module instead, so check the controller series before ordering.