The CompactLogix L32E vs L33ER: Which controls more I/O?

L32E vs L33ER FiRecently I’ve been running into the perception that Rockwell’s new 5370 CompactLogix controllers have the ability to control less I/O than previous models.

To address this question, today we’ll take a look at the 1769-L32E versus the 1769-L33ER to see which one of these CompactLogix processors can control the most I/O.

L32E vs. L33ER: Local I/O

Number of local I/O modules supported by L32EWe’ll start by comparing the local I/O limits of each model by reviewing Rockwell’s CompactLogix selection guide documentation.


Number of local I/O modules supported by L33ERL32E: Supports sixteen local I/O modules.

L33ER: Supports sixteen local I/O modules.

Winner: Tie

As far as local I/O goes, the L32E and L33ER tie as each support sixteen 1769 local expansion I/O modules.

L32E vs. L33ER: Remote Ethernet Racks of Discrete I/O

2b 1769-L33ER Discrete Ethernet IO LimitsNext we’ll take a look at the number of remote Ethernet discrete I/O racks supported.

Using Rockwell’s Ethernet IP Capacity tool (more on this tool here,) we are able to add thirty two remote racks of Point I/O (or Flex I/O) to the L32E.

3a 1769-L32E Analog Ethernet IO LimitsHowever, we are also able to add a total of thirty two remote racks of discrete Point or Flex I/O to the L33ER as well.


L32E: Thirty two remote racks of discrete I/O

L33ER: Thirty two remote racks of discrete I/O

Winner: Tie

As far as the number of remote racks of discrete I/O, the L32E and L33ER tie again since each support thirty two remote racks of I/O.

L32E vs. L33ER:  Remote Ethernet Analog Modules

3b 1769-L33ER Analog Ethernet IO LimitsNext we’ll add some analog I/O to the mix.

This time we’ll start with the L33ER and the current configuration of thirty two remote Ethernet racks of I/O.

Using this configuration we find we can add up to six analog modules (at an eighty millisecond update rate) to each of the thirty two racks and still be within this processor’s limit.

3a 1769-L32E Analog Ethernet IO LimitsHowever, when we switch over to the L32E we find that with the same six analog modules per rack we can only support a total of four racks.


L33ER: Thirty two racks with six analog modules each

L32E: Four racks with six analog modules each

Winner: L33ER by a very wide margin

As far as which processor supports the most analog modules, the L33ER and it’s expanded number of connections supports many times more analog modules in remote Ethernet I/O racks.

L32E vs. L33ER:  Remote Ethernet Variable Frequency Drives

4a 1769-L32E VFD Ethernet IO LimitsAfter remote I/O, VFD’s are the second most common device I see added to the RSLogix 5000 I/O configuration.

With that in mind, let’s compare the number of VFD’s supported on Ethernet by each processor.

4b 1769-L33ER VFD Ethernet IO LimitsSimilar to our discrete I/O test, we can see here that both the L32E and L33ER support up to 32 PowerFlex 525 drives.


L32E: Thirty two VFDs

L33ER: Thirty two VFDs

Winner: Tie

Bonus Round: Number of HMI’s supported

While not I/O, I thought it would be helpful to also compare the number of HMI’s the L32E and L33ER support.

Before we begin though, I wanted to share this warning from the Ethernet IP Capacity Tool that pops up when adding HMI’s:

5 Disclaimer

5b 1769-L33ER HMI LimitsWe’ll again start with the L33ER.

Here we can see it theoretically supports up to 51 PanelView Plus HMI’s when the HMI project has 200 tags updating at 250ms.

However, when we select the same HMI configuration for the L32E, we find it can theorectically only support six PanelView Plus units.

5a 1769-L32E HMI Limits


L33ER: Fifty one PanelView Plus HMI’s

L32E: Six PanelView Plus HMIs

Winner: The L33ER by a very wide margin

After reviewing the I/O capabilities of both the 1769-L32E and 1769-L33ER above, it’s quite clear that the newer L33ER supports the same number of Ethernet I/O racks.

But, in those racks it can support many more analog modules, as well as theoretically support a substantially larger number of HMIs at the same time.

So with that said, the L33ER is the clear winner of this VERSUS competition.

Winner: 1769-L33ER

I hope you’ve enjoyed this article comparing the amount of I/O supported by the L32E and L33ER.

If you have any comments, questions, corrections or suggesting please feel welcome to leave them with us by filling in the “leave a reply” form at the bottom of this page.


Shawn Tierney
Automation Consultant
Insights In Automation

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