In short
This technical comparison breaks down the hardware, memory, communication options, and performance parameters of the Allen-Bradley MicroLogix 1100 and MicroLogix 1400 controllers, helping automation engineers choose the right replacement parts or plan system migrations.
Overview
For nearly two decades, the Allen-Bradley MicroLogix family of Programmable Logic Controllers (PLCs) has been a foundational standard for small-scale, stand-alone, and decentralized control systems. Within this catalog, the MicroLogix 1100 (Bulletin 1763) and the MicroLogix 1400 (Bulletin 1766) stand out as the only two models in the family featuring integrated Ethernet ports and onboard LCD displays.
Developed to bridge the gap between simple smart relays and high-performance modular PLCs like the SLC 500 or CompactLogix, both models use the classic SLC-based instruction set in RSLogix 500. However, while they share architectural similarities, they target drastically different application scales. The MicroLogix 1100 was designed for basic, low-point-count installations requiring Ethernet connectivity. The MicroLogix 1400, on the other hand, represents the absolute peak of the MicroLogix series, offering higher I/O density, extensive high-speed counter (HSC) configurations, additional serial ports, and considerably greater processing power.
As Rockwell Automation transitions these legacy lines toward obsolete status, understanding their exact differences is critical for maintenance engineers, system integrators, and procurement officers sourcing replacement parts from distributors like Palm Parts Solution.
Key Differences at a Glance
While both controllers share the same physical design philosophy, the MicroLogix 1400 is physically wider and offers significantly more processing power. Below is a comparative overview highlighting the primary differentiators.
| Feature | MicroLogix 1100 (Bulletin 1763) | MicroLogix 1400 (Bulletin 1766) |
|---|---|---|
| Max Onboard Digital I/O | 16 points (10 inputs, 6 outputs) | 32 points (20 inputs, 12 outputs) |
| Onboard Analog I/O | 2 voltage inputs (0-10V DC) | Up to 4 voltage inputs, 2 voltage outputs (on select models) |
| Expansion Modules | Max 4 (1762 series) | Max 7 (1762 series) |
| User Memory | 8 KB total (4 KB program / 4 KB data) | 20 KB total (10 KB program / 10 KB data) |
| Serial Communication | 1x RS-232/RS-485 Combo Port (Channel 0) | 1x RS-232/RS-485 Combo (Ch 0), 1x RS-232 9-pin D-sub (Ch 2) |
| High-Speed Counters | 1x single-phase at 40 kHz | Up to 3x at 100 kHz (on DC input models) |
| Pulse Outputs (PTO/PWM) | 1x output at 40 kHz | Up to 3x outputs at 100 kHz (on DC output models) |
| LCD Backlight Colors | Static (green/blue) | Multi-color diagnostic (normally green, red/orange on fault) |
Specifications Comparison
The table below outlines the core hardware and operational specifications for both industrial controllers.
| Specification Attribute | MicroLogix 1100 (1763) | MicroLogix 1400 (1766) |
|---|---|---|
| HP/kW Range | N/A (Logic controller; commands external starters/VFDs of any rating) | N/A (Logic controller; commands external starters/VFDs of any rating) |
| Operating Voltage Options | 120/240V AC; 24V DC; 12V DC | 120/240V AC; 24V DC; 12V DC |
| Control Mode | Ladder Logic control, basic PID loop processing | Ladder Logic control, advanced multi-loop PID, high-speed motion control |
| Communication Protocols | EtherNet/IP, Modbus TCP/IP, DF1, DH-485, ASCII | EtherNet/IP, Modbus TCP/IP, DF1, DH-485, ASCII, Modbus RTU Master/Slave |
| Memory | 8 Kilobytes (EEPROM backing storage available) | 20 Kilobytes (non-volatile flash backing storage available) |
| Embedded I/O Capacity | 10 Digital Inputs, 6 Digital Outputs, 2 Analog Inputs (unipolar 0-10V) | 20 Digital Inputs, 12 Digital Outputs, 4 Analog Inputs, 2 Analog Outputs |
| Max Expandable I/O | Up to 144 total channels (using 1762 expansion) | Up to 256 total channels (using 1762 expansion) |
| Output Relay Configuration | 2.5 A continuous current per point | 2.5 A continuous current per point |
| Lifecycle Status | Obsolete (Discontinued by OEM in 2022) | End-of-Life transition (Discontinued by OEM in 2024) |
Performance & Capabilities
Beyond basic point-count statistics, these two controllers differ dramatically in execution speed and hardware capabilities.
Processing and User Code Execution
The MicroLogix 1400 features a faster internal processor than the 1100. This provides quicker logic scan times when handling larger data tables and complex instructions. This performance boost is particularly evident when executing Floating-Point Math or PID loop routines. While the MicroLogix 1100 is suited for simple applications like pump control, basic conveyors, or compressor monitoring, the MicroLogix 1400 can easily manage more elaborate tasks, such as multi-axis positioning systems or complex process control loops.
High-Speed Motion and Counting
For motion control and high-speed feedback:
- The MicroLogix 1100 provides a single high-speed counter (HSC) operating up to 40 kHz and a single pulse train output (PTO) up to 40 kHz. This is adequate for simple packaging machines with a single encoder input and stepper motor output.
- The MicroLogix 1400 includes three high-speed counters operating at 100 kHz and three pulse train/PWM outputs rated for 100 kHz on 24V DC output units (such as the 1766-L32BXB model). This makes it capable of multi-axis registration and precise step-control configurations.
Programming & Software
Both families are programmed with Rockwell Automation software, which simplifies integration for teams already familiar with Allen-Bradley instruction sets.
Software Environment
Programming is carried out via RSLogix 500 (Standard or Professional) or RSLogix Micro. RSLogix Micro is a cost-effective, dedicated version of the programming tool designed specifically for the MicroLogix family.
- Programmers use native Rockwell Ladder Logic (A-B format), utilizing standard data files such as Status (S), Binary (B), Integer (N), Float (F), Counter (C), and Timer (T).
- The 1400 includes a wider range of software instructions. It supports up to 14 independent PID loops directly in the controller's background execution task, while the 1100 is limited both by basic processing overhead and standard instruction structures.
Furthermore, because of the larger 20 KB memory footprint (compared to 8 KB on the 1100), programs running on the 1400 can accommodate larger rung counts and more verbose user comments without running out of local data storage.
Communication & Networking
The inclusion of an integrated RJ45 Ethernet port in both the MicroLogix 1100 and 1400 was a major milestone for micro-PLCs. However, their port counts and protocol support differ significantly.
MicroLogix 1100 Comm Ports:
+----------------+ +-------------------+
| Ethernet RJ45 | | RS-232/485 Min-DIN|
| (Channel 1) | | (Channel 0) |
+----------------+ +-------------------+
MicroLogix 1400 Comm Ports:
+----------------+ +-------------------+ +-------------------+
| Ethernet RJ45 | | RS-232/485 Min-DIN| | 9-Pin D-Sub RS232|
| (Channel 1) | | (Channel 0) | | (Channel 2) |
+----------------+ +-------------------+ +-------------------+
Port Availability
- MicroLogix 1100 has two communication channels: Channel 1 (Ethernet) and Channel 0 (an isolated combo RS-232/RS-485 port in an 8-pin mini-DIN format).
- MicroLogix 1400 features three distinct communication interfaces: Channel 1 (Ethernet), Channel 0 (8-pin mini-DIN RS-232/RS-485), and an added Channel 2 interface—a non-isolated 9-pin female D-sub serial port supporting RS-232. This extra port allows users to permanently wire a local HMI (via DB9 serial) and a local SCADA radio modem (via mini-DIN) while keeping the Ethernet port free for remote diagnostics or commissioning.
Protocol Capabilities
Through these interfaces, both devices support DF1 Full-Duplex/Half-Duplex, DH-485, and Modbus TCP/IP. However, the MicroLogix 1400 supports direct Modbus RTU Master/Slave execution on its serial ports, making it much easier to integrate with third-party variable frequency drives (VFDs), power monitors, and process sensors without requiring an external protocol translator.
Pricing & Lifecycle
Both the MicroLogix 1100 and MicroLogix 1400 are mature products and have entered the end of their official lifecycle.
- MicroLogix 1100 (Bulletin 1763): Reached end-of-life status and was discontinued by Rockwell Automation in September 2022.
- MicroLogix 1400 (Bulletin 1766): Reached its official end-of-life transition milestone in March 2024.
Currently, standard factory-new units are no longer sold directly through authorized Allen-Bradley distribution channels. As a result, the market relies heavily on industrial parts suppliers like Palm Parts Solution to source high-quality surplus, remanufactured, or refurbished units.
Market Pricing
Prices on the secondary market for both PLCs fluctuate based on scarcity and model variation (AC vs. DC control power, analog vs. standard digital). Generally, refurbished MicroLogix 1400 units command a price premium over MicroLogix 1100 units because of their superior I/O capacity, high-speed capabilities, and higher demand in legacy systems.
When to Choose Each
Choosing between these two controllers in retrofitting or direct-replacement scenarios depends on specific operational needs.
Choose the MicroLogix 1100 if:
- Physical space is tight: The 1100 is physically smaller (110mm width vs. 180mm for the 1400) and fits easily in tight junction boxes or control panels.
- Replacing an existing 1100 system: If you are direct-swapping an exact model (e.g., a failed 1763-L16BWA) to avoid modifying wiring schematics, cabinet layouts, or the existing RSLogix 500 program.
- Lowest cost is paramount: For basic low-complexity control, a refurbished MicroLogix 1100 is a highly economical way to maintain operation without costly panel modifications.
Choose the MicroLogix 1400 if:
- You need local high-density I/O: The 32 onboard digital points and expandable analog capabilities eliminate the need to purchase additional expansion modules, keeping the overall installation clean.
- Multiple serial connections are required: If you must simultaneously connect an HMI, a barcode reader, or a VFD via serial while using Ethernet for SCADA networking.
- Advanced motion control is needed: Excellent for multi-axis legacy indexers, packaging, or winding processes requiring up to three 100 kHz HSCs or PTOs.
- You are looking for a longer-term stopgap: Since the MicroLogix 1400 was discontinued later (March 2024), parts are often newer and easier to find on the surplus market compared to older 1100 models.
Migration & Upgrade Path
Because the entire MicroLogix catalog is retired or rapidly disappearing, Rockwell Automation recommends migrating existing legacy applications to modern control platforms.
Legacy System Migration Destination
+--------------------+ +--------------------+
| MicroLogix 1100 | -----------> | Micro850 (2080) |
+--------------------+ +--------------------+
+--------------------+ +--------------------+
| MicroLogix 1400 | -----------> | Micro870 (2080) |
+--------------------+ +--------------------+
The Recommended Path: Micro800 Series
For micro-scale control, Rockwell's current standard is the Micro800 Series (specifically the Micro850 and Micro870 controllers), which are programmed using Connected Components Workbench (CCW) software.
- Micro850 is the recommended functional replacement for the MicroLogix 1100.
- Micro870 handles larger I/O capacities and serves as the modern replacement for high-density MicroLogix 1400 implementations.
Migration Considerations
- Software Porting: Rockwell provides a free Code Conversion Tool to translate RSLogix 500 projects (.ACH or .SLC files) into CCW projects. Users should plan for manual review, as specialty commands (like communication instructions or high-speed counter structures) do not always translate directly.
- Wiring Differences: The Micro800 series uses pluggable terminal blocks and different physical form factors. A direct mechanical swap is not possible; expect to modify physical backpan layout drawings and terminal terminal labels during upgrades.
- Maintaining Legacy Platforms: Because panel re-engineering and program conversions can be costly and labor-intensive, sourcing refurbished MicroLogix replacement parts from Palm Parts Solution remains a highly effective way to keep your operations running smoothly without the immediate need for a full system upgrade.
Frequently Asked Questions
1. Can a MicroLogix 1400 program run on a MicroLogix 1100?
Generally, no. A program written for a 1400 cannot be downloaded directly to an 1100 because of the 1100's smaller user memory (8 KB vs. 20 KB). Additionally, the I/O configurations, data arrays, and specialized instruction sets of the 1400 are not supported by the 1100's hardware architecture.
2. Can I use 1762 expansion modules on both controllers?
Yes. Both the MicroLogix 1100 and MicroLogix 1400 use the same 1762 expansion I/O standard (e.g., 1762-IQ16, 1762-OW16, 1762-IF4). However, the 1100 supports a maximum of 4 expansion modules, while the 1400 supports up to 7.
3. Are the ethernet ports on the 1100 and 1400 identical?
While both support EtherNet/IP and Modbus TCP/IP, the MicroLogix 1400 features a faster internal network processor. This allows it to handle higher data throughput and support more simultaneous TCP connection sockets than the MicroLogix 1100.
4. Is the programming software for these PLCs free?
Rockwell Automation offers a free version of its programming software called RSLogix Micro Starter Lite. This software can program any model in the MicroLogix 1100 family without requiring a paid license. However, to program the MicroLogix 1400, you will need a standard licensed version of either RSLogix Micro or RSLogix 500.
Related Articles
- Selecting and Installing 1762 Expansion Modules
- How to Back Up Legacy RSLogix 500 Projects
- A Guide to RS-232 and RS-485 Interfaces on MicroLogix Family PLCs
- Migrating MicroLogix to Micro800: Hardware and Software Strategies