In the “good old days,” it seemed like every manufacturer had its own protocols at each level of control. One advantage of this was clear separation of “control” data from “plant” data. However, these older protocols had lower speeds and provided less information on the devices and processes that were connected to them. And, because data throughput and basic transmission rates were relatively low, these networks typically tolerated more variability in cabling and connector integrity.
Ethernet has been in use at the top control levels for decades, and it has steadily migrated into lower levels of control. While there are certainly legacy systems in place and some greenfield installations are using device-level networks for sensors and actuators, the majority of data is transferred via some flavor of Ethernet.
To address concerns about throughput or IT-oriented traffic interfering with plant control, multiple Ethernet networks and subnets are deployed and handled with managed switches and routers. A parallel trend with Ethernet at different levels has been an increase in the amount and types of data being transferred. It’s not unusual for conventional TCP/IP to coexist with other protocols “on top of” TCP/IP and along with video.
The net result is that physical cabling is being pushed to the limit. Whether the cable is Cat5e at 100MHz, Cat6 at 250MHz or Cat6A at 500MHz, you will want to be sure that it meets its specifications. After all, cable is the foundation of network communications.
Often overlooked by plant manufacturing managers, industrial Ethernet certification is vital to overall efficiency and can mean the difference between optimized productivity and less-than-robust performance. In fact, it’s estimated that 35% to 80% of total failures in plant automation can be attributed to the cabling. Loss of critical data, system downtime or even catastrophic, overall failure are possible outcomes of unreliable network performance.
When installing cabling for industrial Ethernet applications, you can’t simply assume it will work. To reduce the risk of startup problems and minimize future downtime, it’s advisable not only to ensure that cable is installed properly but also have it configured, tested, and certified. Cable certification ensures that the cable infrastructure meets standards for quality and speed. Cable certification test parameters include cable length, ACR-N, propagation delay, return loss, and loop resistance. The odds of communication failure increase if these parameters are out of specification. For many cabling and network infrastructure vendors, certification is a requirement for installation warranties.
In commercial sectors, certification is relatively common. However, in the industrial space, it’s relatively uncommon. Therefore, when researching your options for cable testing, it is important to remember that not all certifiers are created equal. Certifiers have active electronics at each end of the cable that work together to conduct measurements. Look for a certifier that can be operated from either end to avoid the need to walk back to the “head” end during testing.
Industrial installations may have RJ45 to M12, RJ45 to RJ45, or M12 to M12 cable connections. Some using M12 connections may have both the older M12 two-pair cabling or the newer four-pair cabling, so find a certifier that can handle either. The Telecommunications Industry Association (TIA) has specifications for all of these variations.
Also, Cat5e (100MHz)/6 (250MHz) and, increasingly, 6A (500MHz) copper cabling is in use in industrial installations, so you may want your certifier to support the emerging Cat8 with expected applications in areas such as data centers.
Finally, the connection types discussed so far have all been for copper cabling. Your application may benefit from the noise immunity and intrinsic safety of fiber. In this case, make sure the certifiers you are considering also have adapters for single and multimode fiber.