Complete Guide on Buying Your First Allen Bradley PLC for Programming

Introduction

PLC Programming is challenging; it doesn't have to be costly. We recommend that those who are looking to get into this career invest in an entry level PLC that allows them to practice without breaking the bank. Once you land your first job, you may choose to purchase additional hardware. However, the emphasis of this tutorial is on those who are just getting started and/or are going through some of our Allen Bradley PLC Training tutorials..

Our PLC of Choice: MicroLogix 1100 Series

Note: You may choose to purchase a Siemens, Omron, Opto22, or a different PLC depending on your goals. Our focus is getting up to speed on the Allen Bradley platform.

Supporting Documents

MicroLogix 1100 Datasheet

Why MicroLogix 1100?

1. Industry Standard | The MicroLogix 1100 PLCs are still widely utilized across the industry. You can find them in smaller machines and processes in many industries.
2. Low Cost Allen Bradley | The MicroLogix 1100 PLCs are an inexpensive entrypoint (From an Allen Bradley standpoint) into learning PLC Programming and a job in automation.
3. Free Programming Software | The free RSLogix 500 version that can be downloaded directly from Rockwell is only compatible with the MicroLogix 1100 series of PLCs.
4. EtherNet Connectivity | Almost every device on the production floor communicates over EtherNet/IP. It is important to choose a PLC that has this protocol.
5. Wide I/O Available | The MicroLogix series has a wide range of expansion cards with various Input and Output options.
6. Mature Product | The MicroLogix 1000 PLC is widely documented and has plenty of materials outlining issues, configurations, applications and more.

Basic Components

Before we dive into the purchase process, let’s look into the MicroLogix 1100 documentation in order to determine the options available to us. We should also pay attention to any additional components we may need.

The table above contains critical information about the four (4) controllers we can choose from. Let’s go over the key differences:

• “Input Power” | Dictates the power source required to power ON the controller. The 120/240VAC controller may be powered directly from the outlet. For the 24VDC and 12-to-24VDC controllers, you will need an external power supply. For first time buyers, we recommend going with the 120/240VAC option.
• “Digital Inputs” | Dictates the digital inputs available on each controller. You may choose between the 120VAC and 24VDC standard. For first time buyers, we recommend going with the low voltage (24VDC) option.
• “Analog Inputs” | Dictates the analog inputs available on the controller. The four options are the same.
• “Digital Outputs” | Dictates the digital outputs available on each controller. The high-speed output on the 3rd controller may be useful in the field, but should not play a big impact on the learning process. For first time buyers, we recommend going with the least expensive option.

Key Takeaways

• Two of the controllers will require an external power supply. That being said, you’ll most likely need a power supply for external components regardless of your PLC.
• One of the controllers has 120VAC inputs. You’ll need to purchase appropriate external components if you want to utilize the inputs.

Purchasing Your First PLC on eBay

We’ve talked about this before. As a first time PLC buyer, it may be difficult for you to purchase hardware from a distributor. That being said, if your employer is able to sponsor a training kit, we recommend going that route.

Step 1 - Go to https://www.ebay.com/

Step 2 - Search for the first PLC type - 1763-L16AWA

Step 3 - Order Listings by “Price + Shipping: Lowest First”

Step 4 - Identify “Proper” PLC Listings‍

Look through the listings and find what looks like a decent PLC. You don’t want to purchase an I/O module, a broken PLC, a “For Parts Only” component, etc. Click the listing and read through the description from the vendor. Lastly, it’s important to note that the country of origin may affect the quality of the PLC you will receive. There are known refurbishers in many parts of the world that will sell a PLC as new when it is not. We recommend to purchase local!

Note: certain PLC modules may have damaged I/O ports and are often disclosed as such by vendors. We recommend purchasing PLCs with all working I/O points.

Step 5 - Write Down the Price of the Model

As of March 29 2021, the least expensive 1763-L16AWA MicroLogix 1100 is 197 USD.

Step 6 - Search for the second PLC type - 1763-L16BWA [Steps 2 - 5]

As of March 29 2021, the least expensive 1763-L16BWA MicroLogix 1100 is 249 USD.

Step 7 - Search for the second PLC type - 1763-L16BBB [Steps 2 - 5]

As of March 29 2021, the least expensive 1763-L16BBB MicroLogix 1100 is 275 USD.

Step 8 - Search for the second PLC type - 1763-L16DWD [Steps 2 - 5]

As of March 29 2021, the least expensive 1763-L16BBB MicroLogix 1100 is 277 USD.

Making a Purchase

At this point, you’ve reviewed the four options available through eBay. Based on our numbers, the most cost effective hardware is the 1763-L16AWA at 197 USD.

External Power Supply for the 1763-L16BBB and 1763-L16DWD

As discussed above, you’ll need to purchase an external power supply in addition to the main unit if you choose to go with these models. Follow steps 2 - 5 listed above to find a suitable inexpensive power supply.

Step 9 - Search for “24VDC Power Supply Din Rail” [Steps 2 - 5]

Note: You’ll get a wide variety of hardware when you search for “24VDC Power Supply” on eBay. You’ll find everything from diodes to stand-alone PCBs. We recommend that you search for din rail based power supplies as that is what you’ll see in the field and you can mount them on the same din rail as the PLC.

Note 2: You should select a power supply that will provide at least 3A of current.

Note 3: It may be tempting to purchase an Allen Bradley power supply to match the PLC. We recommend purchasing a “SOLA” brand power supply as a cost effective option.

Conclusion

It’s difficult to choose your first PLC to learn PLC programming. We recommend that those of you who are looking to work in an Allen Bradley based environment consider the MicroLogix 1100 series of PLCs. These cost effective PLCs are used in the field, are cost-effective, are compatible with the free version of RSLogix 500 and allow you to practice nearly every feature you need to master.

If you have any trouble choosing a unit, identifying if the listing is adequate or otherwise, don’t hesitate to post on the form or reaching out to us directly.