There is a new industrial revolution. It’s combining advancements in machines and controls with advancements in computing and communications from the Internet revolution. Today’s technology is being applied in ways not even thought of even 10 years ago to solve problems and increase industrial productivity.
That’s where the challenge of mixing new and existing technologies in an industrial environment comes in. Here are four problem-solving technologies for industrial networking.
1. Fiber for distance and EMI/RFI immunity. Fiber optic cable is often the preferred cable choice in industrial environments because it can cover very long distances and offers immunity to electrical interference.
Fiber doesn’t have the 100-meter distance limitation of twisted pair copper, so it can support distances from 300 meters to 40 kilometers, or more, depending on the style of cable, wavelength, and network.
Fiber also provides extremely reliable data transmission. It’s completely immune to many environmental factors that affect copper cable. The fiber is made of glass, which is an insulator, so no electric current can flow through. It is not affected by electromagnetic interference and radio-frequency interference (EMI/RFI), crosstalk, impedance problems, and more. You can run fiber next to industrial equipment without worry.
2. A ring topology for redundancy. Although Ethernet is usually thought of as having a star topology, it’s possible to build an Ethernet network as a ring. This is often used in applications where it may be difficult to run fiber in a star formation from a central switch, such as in industrial or even traffic signal applications.
One industrial networking scenario involves connecting industrial devices, such as computer numeric controlled (CNC) machines, to hardened Ethernet switches. The switches are set up in a ring topology for maximum reliability with a failover time of less than 30 ms, which is virtually instantaneous. The ring has the advantage of providing a redundant pathway if a link goes down. If one part of the ring fails, traffic will automatically reverse direction.
3. Machine vision and USB 3.0. Machine vision is an image-based automatic inspection technology that is now an indispensable tool for quality assurance, sorting, and material handling in every industry, including electronics, food processing, pharmaceuticals, packaging, automotive, etc. Machine vision technology incorporates cameras, PCs, software, and other hardware to automatically take pictures and inspect materials as they pass along an assembly line.
Machine vision is an economical way to make sure sub-spec product is rejected. It can be used to inspect for geometry, placement, packaging, labeling, seal integrity, finish, color, pattern, bar code, and almost any other parameter you can think of.
USB 3.0 greatly enhances machine vision systems. Because of USB 3.0’s 5-Gbps throughput, ten times more than USB 2.0, it eliminates problems of stability and low latency for image transmission and camera control. USB 3.0 enables the transmission of higher-resolution, higher-frame video with no loss of quality.
4. Industrial serial connections. Industrial control is a designation for the devices that interface with machinery such as packaging machines, generators, lathes, and even scales. Although most of today’s IT runs on Ethernet, industrial devices often use an RS-232, RS-485, or RS-422 serial interface. To capitalize on the investment in the industrial equipment and machinery, interface converters and line drivers can be used to provide the link between older RS-232/422/485 equipment connections and newer USB and Ethernet networks.
RS-232 transmits data at speeds up to 115 kbps and over distances up to 50 feet, although higher distances can be achieved by using low-capacitance cable. Both sync and async binary data transmission fall under RS-232. Although the original RS-232 connector is DB25, DB9 and RJ-45 connectors are now more common. Also, industrial devices often use a terminal block instead of a connector for the RS-232 interface. RS-232 is somewhat restricted as an industrial interface because of its restricted range and because it only supports point-to-point links.
For a far more detailed study of industrial communications, see the white paper: Elements of an RS-422/RS-485 System.