Programmable Logic Controllers are placed at the heart of the manufacturing process. If they’re the heart, the veins which link them to other field components are the network. Deploying a control systems network can be challenging & without proper tracking and implementation may lead to complications.
A young organization may choose to track their network infrastructure through a simple Excel spreadsheet. This method is prone to errors on larger scales, but it very easy to manage and visualize for small networks. I manage a private home network of over 20 devices through Excel.
The technical component of visualizing an Allen Bradley PLC, HMI, VFD, etc. network is RSLinx. This software package provides an interface that can be used to scan an entire subnet & map the devices to their appropriate IPs. Furthermore, RSLinx is the software Allen Bradley devices utilize to connect to the user computer.
We will be exploring the basics of networking as well as the RSLinx Classic driver setup within this article.
A simple spreadsheet is used to track the different subnets of a network. In my case, I’m using a private network with the IP address of 192.168.1.xxx where xxx is the last octet address assigned to a specific device. The columns are strategically created in order to track the octet, device, device type, software, physical location, data verified and the owner of the device. Lastly, the rightmost column provides a section for miscellanious notes which are most commonly used to store a password for the device.
The spreadsheet above can be seen to have devices at specific IP addresses. For example, a “Cognex Camera” is found at the IP of 192.168.1.15. Similarly, other items are found at their respective addresses.
RSLinx is the networking tool from Allen Bradley. It allows the user to create miscellaneous drivers that connect to a specified field device. RSLinx is a straightforward application with confusing driver configurations. When it comes to the EtherNet/IP protocol, the user has two options: Ethernet devices and EtherNet/IP Driver. Either one can be created from the “Configure Drivers” prompt within RSLinx. However, their setup and interface are different & need to be set up differently.
The “Ethernet devices” driver allows the user to granularly specify each device. In other words, you’ll have to enter the IP address of each device that you’re looking to communicate with. The advantage of this method is that you’re limiting yourself to the devices you specify. This translates to a much more controlled method of communication & eliminates user mistakes.
Once each device is specified, the driver will start pinging those devices only. Therefore, it’s easy to see if the devices added to the tree are available on the network.
The “EtherNet/IP Driver” driver allows the user to send an ARP message to an entire subnet & map all the devices onto the driver. This method is much simpler to execute on a large network but may confuse inexperienced programmers. It’s easy to connect to the wrong device from a list of many and to make unwanted changes to the device.
Here’s an example of a network mapped through this driver:
As you’ll quickly notice, it’s best to use a combination of the two drivers in a real-world scenario. I would typically start by mapping an entire network followed by setting up key drivers mapped to individual components.
Knowing how to manage a PLC industrial network is extremely important. Although there are advanced methods in large scale plans, a simple Excel spreadsheet can be utilized for small to medium networks without any problems at all. This approach is easy to implement and allows the user to track the different assets as well as configurations on the network.
RSLinx is the software that is used to connect to most Allen Bradley devices such as PLCs, HMIs, VFDs and more. It’s important to know how to create drivers within the application and how to utilize them accordingly. There are two types of EtherNet drivers a user may create. One should be used to scan an entire network while the other will only scan a single device at a time.