The requirement for reliable, rugged connectors in transit and transport has never been more important
By: Engineering Staff, Elma Electronic
Rugged Connectors Ensure Reliability for Data-Driven Railway Applications
Despite the unknown changes afoot with the new U.S. administration, railway as a means of mass transport and transit isn’t going anywhere anytime soon. Over the next few decades, technological developments within the railway industry will bring badly needed updates to vehicle controls, security, communications, and entertainment features. Most importantly, it will improve Positive Train Control (PTC), a safety system in which train movements are electronically monitored and controlled.
A critical element of these systems is the connector technology that allows data being generated across the various railway systems to be quickly accessed for critical decision making. The various systems within the railway network need to talk to one another for safe, efficient operation. Rugged interconnections ensure this happens.
As more electronics are packed into these environments, connectors are not immune to the scrutiny placed on every component within a system to do more in less space. With the railway industry looking for connectors that still uphold industry regulations as well as meet current technology requirements ̶ such as enabling an Ethernet connection ̶̶ connectors need to keep current with the times. (Figure 1)
Withstanding the Harsh Environment
EN50155 is the primary international standard covering the use of electronic equipment on rolling stock for railway applications. The standard covers temperature, humidity, shock, vibration, and other parameters of electronic equipment. Environmental requirements can be very stringent; some equipment needs to meet shock conditions up to 50Gs and temperature ranges of -40°C to 85°C.
M12 connectors are fast becoming the connector method of choice for future rail systems. They are desirable for use where a reliable connection system with environmental protection is required, such as rolling stock and wayside applications. The M12 connectors provide a future-facing interface that supports higher-bandwidth needs, meeting requirements up to 10Gb/s.
Rail transportation applications are becoming especially cognizant of connector technology, with options due, in part, to the growing amount of data being pushed digitally across modern infrastructures combined with shrinking system footprints. Fortunately, the M12 connector interface has been subjected to rigorous use in other industrial applications and has shown itself well suited to meet EN50155 for rail.
Not to be forgotten during upgrade rollouts, however, are older interface technologies, which must still be supported. Fieldbus interfaces, for example, to RS-232, RS-485, and CANBus must live side-by-side with newer interfaces such as Ethernet, WiFi, and GPS, to name a few. Replacing the older connectors are smaller, more robust connectors that are better aligned with the demands of high-speed, data-driven systems operating in harsh environments. These connectors also meet the industry requirements put forth in the EN50155 standard (Figure 2).
Meeting Today’s Data Demands
Connectors that mimic the electrical and mechanical performance of traditional rail transportation interfaces, yet meet the ever-increasing requirements for high-speed interconnect solutions, give designers the best of both worlds. Typical high-speed signaling requirements include Ethernet 10GBase-T, USB 3.0, DVI, DisplayPort, SATA 3.0, and HDMI.
Two main areas of development in these newer ruggedized connectors are 1) the technology within the connectors themselves, and 2) the cables required to harness the interconnects to the more sophisticated electronic equipment.
More Than Just Mating
Reliable coupling and optimization for harsh environments aren’t the only important considerations. Connectors must also offer the high performance, reliability, and signal integrity necessary for computer systems in wayside and rolling stock.
Design challenges that might be encountered along the way:
- What is the intended temperature range, level of sealing, and shielding requirements of the specific application?
- How many contacts are needed?
- Is there a target number of mating cycles the connector needs to withstand?
- What about material and locking types?
With the increased data throughput of more modern, rugged connectors comes the concern for the cables used to route the data across the network paths. Just as connector technology was slower to develop, cable manufacturers have followed suit with new cable designs that may not quite meet the needs of these newer connectors.
The design challenges need to take into account several issues:
- Connector types, such as straight or right angle
- Cable types, such as regular coaxial, semi rigid, and rigid
- Requirements for length matching (e.g., the longest cable determines the length of the others in that grouping, when all the cables are routed throughout the chassis)
The key to incorporating the right cables is using suppliers that specialize in this field, because they have the knowledge, the know-how and the latest test equipment to produce a finished product that will meet the needs of a given project.
Connecting a Modern, Rolling World
Today’s connectors are meeting the requirements of a modern, rolling world with smaller packages, while handling the increased data throughput of high-speed networks. Electronics are getting faster and smaller; yet they are still able to successfully meet the specific data and environmental requirements in railway applications by using faster, more rugged connectors that provide reliable communications.