Introducing ControlLogix controllers

ControlLogix consists of a common control engine with a common development environment and tight integration between the programming software, controller, and I/O modules. This close integration greatly reduces the automation engineering development time and cost.

The following is a diagram that details the look of a typical ControlLogix L5 processor card:

We will next discuss the following ControlLogix controllers in the upcoming subtopics:

• ControlLogix Series 6 controllers (L6)
• ControlLogix Series 7 controllers (L7)
• ControlLogix Series 8 controllers (L8)

ControlLogix Series 6 controllers (L6)

In 2002, the Bulletin 1756 ControlLogix L6 processor was released with a more powerful processor and more memory, and the CompactFlash non-volatile memory card was added to the lineup. The ControlLogix L6 came in two different flavors—Series A and Series B. Series A processors used volatile memory and required a battery to maintain the program and user memory when power to the controller was disconnected. The Series B processor had internal non-volatile memory, which did not require a battery to maintain the current program.

The following photo shows a typical ControlLogix L6 processor card:

In the next section, we will introduce the Series 7 ControlLogix controller, also known as the L7.

ControlLogix Series 7 controllers (L7)

In 2010, Rockwell Automation launched the Series 7 (also referred to as L7 and ControlLogix 5570) controllers.

The following is a diagram of the ControlLogix 5573 controller, featuring the four-ASCII-character LCDs and an SD card slot:

The ControlLogix Series 7 controller featured the following enhancements over the Series 6 (L6) controllers:

• Twice the performance capability due to a more powerful dual-core CPU.
• Adoption of modern Synchronous Dynamic Random Access Memory (SDRAM) memory.
• The replacement of the nine-pin serial port with a USB 2.0 port (programs transfer 200 times faster over USB 2.0 than serial).
• The replacement of the CompactFlash memory card with an SD memory card.
• The replacement of the lithium battery with the capacitor-based Energy Storage Module (ESM). The ESM provides power to the controller in the event of a power loss to allow it to copy the contents of its memory from volatile memory to the onboard non-volatile memory. The ESM eliminates the issue with L6 series controllers where they would lose the program after a few weeks without power once the battery was completely drained.
• The ability to store program comments and tag descriptions on the controller (firmware v21 and higher).
• Addition of the onboard four-character display.

We have learned in this section that there are many improvements in the L7 controllers over the L6, providing more power and reliability. In the following section, we will introduce the latest ControlLogix controller series, known as the L8.

ControlLogix Series 8 controllers (L8)

In 2015, Rockwell Automation released a new series of faster controllers called Series 8 (also referred to as L8 and ControlLogix 5580). The L8 model provides several improvements over the L7 series of controller, including the following:

• A CPU performance increase in the range of 5 to 20 times compared to the L7 series
• 20% more memory over the L7 series
• Larger memory cards (SD cards), with 2 GB cards as opposed to the 1 GB models that come with the L7 series
• A 10-fold increase in network speed with support of up to 1 GB (compared to the 100 MB connection supported by the L7 series)
• Support for CIP Security (more information on this is covered in Chapter 14, Understanding Cybersecurity Practices in Logix)

Finally, because the L8 controllers have an Ethernet/IP card integrated into the controller itself, there is no need to purchase a separate 1756-ENBT (Ethernet/IP card), which makes the L8 slightly cheaper than purchasing an L7. The following diagram is of a ControlLogix 5585E and features the front connection ports for Ethernet and USB:

In the next section, we will cover some of the data points you will need when selecting a ControlLogix controller.