MicroLogix 1500With the recent announcement from Rockwell Automation that the MicroLogix 1500’s status has been changed to “End of Life,” many are asking, “What’s the best Micro to migrate too?”

Since the 1500 has some unique features, in order to suggest a replacement we need to which are being used, as well as how many expansion I/O modules are needed.

UPDATE: Rockwell has released a new document detailing MicroLogix 1500 migration options, and a link to that manual is below:

Most compatible option, good when only a few expansion modules are needed.

MicroLogix-1400-Expansion-IO-FiIf you’re looking to replace the MicroLogix 1500 with a micro that can re-use the existing program, requires little to no retraining, and you’re not using more than a few expansion I/O modules, my choice would be the MicroLogix 1400.

This is because the MicroLogix 1400 is programmed just like the MicroLogix 1500, using the very same programming software which easily converts 1500 programs to the 1400.
The MicroLogix 1400 also has the same programming ports as the MicroLogix 1500, including an 8-Pin Mini Din port as well as a 9 pin D-shell port.

The 1400 also has the added benefit of a built-in display with features similar to the 1500’s DAT module. And it also has a built-in Ethernet port and supports online editing.

However, unlike the MicroLogix 1500 which has a 24 or 28 point base and supports 16 Compact I/O expansion modules, the MicroLogix 1400 has a 32 point base and only supports up to seven of the less dense 1762 expansion I/O modules.

So while the 1400 is a worthly replacement for 1500 application with only a few expansion modules, for those systems making full use of the 1500’s expansion capabilities the 1400 is not a viable option.

Option for systems with a large number of expansion I/O modules.

CompactLogix L3If your MicroLogix 1500 system is using many or all of the supported 16 Compact I/O expansion modules, you may find your best option is to migrate to the CompactLogix L3xER processors.
This L3xER option allows you to continue to use the same Compact I/O as the 1500, and the number of total I/O will determine which of the three L3xER processors you use.

However, the CompactLogix L3xER processors don’t come with any built-in base I/O like the 1500. This means in addition to the expansion I/O modules you already use with the 1500, you’ll also need expansion I/O to replace the 1500’s base I/O.

The CompactLogix  line of processors also don’t use the same software as the MicroLogix line, however the software does support importing the ladder logic from the 1500’s program with the majority of the ladder instructions functionally identical.

Being able to import your MicroLogix program saves substantial amounts of time over re-entering your code, however the old I/O addresses will need to be mapped to the new I/O tags, and you’ll likely have to make some other minor tweaks.

It should also be noted that the CompactLogix L3xER family does not come with a serial port, but instead has a USB port for programming as well as a built-in two port Ethernet switch.

Note: Rockwell has been recommending the CompactLogix L1xER and L2xER as additional migration options for MicroLogix 1500 users, however neither option supports many local expansion I/O modules.

So in order to use an L1xER or L2xER to replace a MicroLogix 1500 with several expansion modules, you’d need additional I/O located on an Ethernet/IP network.

In Summary

IMicroLogix 1500 to 1400 or CompactLogixf you can fit your I/O requirements into the MicroLogix 1400 and 1762 expansion I/O, that’s going to be the best solution as you can continue to use the same programming software, the same program (after changing the processor type,) and you’ll also have the same serial communication ports as the MicroLogix 1500.

However, if your current MicroLogix 1500 system uses more I/O than the MicroLogix 1400 supports, by migrating to the CompactLogix L3xER family you’ll be able to continue to use Compact I/O, and you’ll also be able to import your MicroLogix 1500 code.

That said, the CompactLogix L3xER models have no built-in I/O, so you’ll be required to add additional modules to replicate the base I/O found in the 1500.

And finally, the CompactLogix has no serial ports, and does require you use a different programming package (RSLogix 5000 v20 or Studio 5000) which you may have to purchase if you don’t already have it.

I hope the above article exploring migration options from the MicroLogix 1500 was helpful.
If you have any comments, questions, or suggestions, please don’t hesitate to share them by using the “post a comment or question” link below.

Until next time, Peace ✌️ 

Shawn M Tierney
Technology Enthusiast & Content Creator

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Shawn Tierney



  1. L1? series with local Point I/O will expand to a fairly large system locally, power injection required.
    Can the Point I/O RS232 module be used for serial communications in slave mode?

    • D,
      Thanks for your comment.
      I agree the L1x is a good choice for smaller systems. However, since it can only take from 6 (l16x) to 8 (L18x) Point I/O local expansion modules, it’s still nowhere close to the 1500’s 16 local modules of the higher density Compact I/O.
      Of course you could add more I/O to the L1x via Ethernet, and that might be the right solution for some folks.
      As far as using Point I/O for RS232, well it depends on what you need it for. I’ve used both the Modbus and ASCII Point I/O modules and they work well.
      But, I have yet to find any information about a “rumored” Point I/O DF1 module, so at this point I would say there’s no option for that yet.
      Thanks again,
      Shawn Tierney

      Join my free community to follow along! You can also become a member and support our work at: Automation.Locals.com


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