Category Archives: Other Industries

Common CAN bus Problems: A Troubleshooting Guide

CAN bus systems are essentially high-speed freeways for digital information exchange within a tightly-packed and complex electrical system such as within an automobile. These tight spaces can’t fit a computer so Controller Area Networks (CAN) help bridge the gap to allow microcontrollers and other devices to “talk” to one another. But what happens when there’s an issue with a CAN bus system? Can you work on a CAN bus cable? How do you diagnose CAN bus problems?

To answer these questions and more, today’s LiveWire spotlight deep-dives into the complex world of CAN bus systems. We’ll cover common CAN bus problems and walk through troubleshooting and diagnostics with these intricate systems.

CAN Bus Wire & Cable Systems 101

CAN bus systems are vital components of the communication system within a vehicle, medical device, industrial control system, or other highly-complex yet space-constrained application. Within a vehicle, this allows form the different control modules to all talk to one another at the same time. Vital safety systems like the anti-lock brakes communicating with the engine’s own module, parts of the transmission, and more are then all displaying real-time information to the driver via the instrument cluster. This type of sophisticated communication requires cables and wires to be specifically engineered for the rigorous demands they’ll undergo. 

When CAN bus systems are working correctly, they’ll send and receive the data they are transmitting within a set of frames. Even with a closed system like a vehicle, the data is sent via a code that helps control modules prioritize the data that’s being sent. Within the code that’s coming from a control module, the code being sent has certain values that can designate the priority of a given message. This helps control the flow of data that’s going through the CAN bus system so that really important data, such as something related to a safety system, can be sent and received ahead of data that’s operationally generic. 

Within the code is also all of the data that needs to be transmitted in that instance from one control module to another. Think of your vehicle driving through snow or water and your vehicle automatically rotating tires at different speeds to compensate. This action may seem mundane when you drive everyday, but the intensely-complex actions to get there were all thanks to the CAN bus system crunching the data frames to communicate the proper action to take in the given situation. 

When the data is transmitted from one control module, the receiving module should always run a validity test on the incoming data to make sure it’s valid. This process is called a checksum and acts as a sort of checks and balances for the module sending the data. When the receiving module validates the data, it responds with acknowledgement of the validity to the transmitter and the system continues to operate as it was intended. When a checksum is not returned valid, a host of issues can develop which we’ll cover in the troubleshooting section below.

Different Types of CAN Bus Subsystems

There’s three types of CAN bus subsystems that help make it possible for different data transmission requirements. When performing within their specifications, these systems facilitate different types of communication between control modules simultaneously and without interference. 

The three types of CAN bus subsystems include:

  1. High-Speed CAN bus subsystems: used for speeds all the way up to 125 KB per second. The construction of the CAN bus high-speed wires creates an effect of opposing voltages. These properties are useful to help cancel out RMF.
  1. Medium-Speed CAN bus subsystems: will handle anywhere from 10 KB to 125 KB per second. These systems are usually made with a single wire that can be shielded to combat interference.
  2. Low-Speed CAN bus subsystems: for handling speeds that are generally 10 KB per second and lower via a single wire set-up. For these systems, wire engineers typically create a centralized control module that then controls other modules in the network.

When there’s an issue within the CAN bus system, a myriad of different concerns can occur. With a vehicle, for example, this may mean the vehicle ceases to run at all. Figuring out what you’re dealing with in a CAN bus system failure can be difficult but we’ll cover some common things to look for that may give you a hint at the issue. 

Spotting Issues Within a CAN Bus System

CAN bus systems have a lot of data flowing through their subsystems at any given moment. If the CAN bus wiring components aren’t performing up to spec, there can be major issues at play within the system. Many of the issues related to wiring can include poor-quality wiring, terminations done incorrectly, or using several different frequencies within a single CAN bus. 

Here’s a few different things you can look for as you diagnose a CAN bus system:

  • Make sure to have the perfect termination resistance. You can use a multimeter to measure this resistance present between the CAN low and high systems. An unpowered system typically runs at 60 Ohms and has two separate termination resistors. 
  • Any form of termination resistors must be located at the endline of the CAN bus system. These termination resistors will perform their best when they are located with precision. 
  • In general terms, the CAN bus system network resembles that of a tree. Believe it or not, the dimensions of the “tree” matter and even a slight variation can wreak havoc on the data integrity. This also goes for the lengths of several different CAN bus wires.
  • The majority of CAN bus wires should be twisted pairs. Twisted pair cables will take two different insulated wires and twist them together so as to run parallel to one another. This is used to combat the interference we discussed above.
  • When using a shielded cable on a CAN bus system, it’s important than only one side be grounded. Otherwise a situation called a grounded ground loop can occur and cause interference. 
  • To that, all the different network devices need to share the same ground so that ground loops don’t occur.

These are just some of the many different avenues you can take when trying to diagnose your CAN bus wire issues as the system is complex and subject to a lot of variables. For example, when the electric system has experienced a surge, it can wipe memory and cause malfunctions in the control modules. 

If you have issues that are above your head, contact our team. Our engineers can help diagnose your CAN bus system and suggest the best fix for your unique situation. 

Fixing Common CAN Bus Problems 

Running through the above can help you find the area of emphasis needed to repair CAN bus system issues. Fixing three of the more common problems that can befall a CAN bus system include:

  • Check over the CAN bus wiring

Ensure everything is solidly connected. All the wire junctions should have a strong solder and splices that are secure. You never want to see a junction that has a simple twist or wire nuts keeping it secure. You also don’t want to see things like terminal blocks, as they can end up distorting the bus wires’ signals. 

  • Pay attention to any stripped sections.

Stripping wires on a CAN bus system can easily lead to damaging sensitive components like the insulation. Without the insulation there to perform its job, interference can occur. Look over the system for any signs of junctions or sections that have been stripped and inspect the quality of the work. 

  • Test the termination, voltage, ground, and resistance levels.

The specifications for each of these can vary depending on the manufacturer so always test according to specifications. Within each of these fundamental tests you should find your CAN bus system performing in line. The smallest variations can add up to major sources of interference.

Seems simple but these complex systems rely just as much on quality components from the very first strand of wire onto the final wire harness that organizes the system in its intended environment. Meridian’s engineers sweat the details like these so that our customers don’t have to.

Using an Oscilloscope to Pinpoint CAN Bus Issues

When analysing waveforms with the use of an oscilloscope, you can actually spot the spikes where an error is occurring. An oscilloscope is an electric test that simply displays the system’s signal voltages. This is usually for more than one signal and presented as a function of time. The waveform has properties every wire engineer knows and loves like amplitude, frequency, and interval time. 

Using tools like an oscilloscope can help you spot differences between the mirror images of frequency and amplitude. Certain issues like a termination resistor failure or simply a communication malfunction present between control modules creates characteristic waveforms that a trained eye can easily spot.  

Start a CAN Bus Cable & Wire Order

Contact our team now to discuss the needs of your project and get the process started.

Truly complex coil cords

Many sensor arrays are complex, and often they need a complex cable connecting them to their processing equipment.  We designed a cable with 8, 28awg conductors, 5, 34 awg Litz® wires, 2, 21 awg power conductors and 3, 0.060” diameter coaxial cable.  Here is what the cable ended up looking like in cross-section:

TRULY-COMPLEX-COIL-CORDS-graphic-A However there was a twist, pun intended.  The customer wanted this cable turned into a coil cord that could slide inside a telescoping tube with an inside diameter less than an inch. Needless to say this isn’t the run-of-the-mill coil cord design. First we started with the custom cable. Our customer had very specific criteria for each of the conductors.  We worked closely with our customer’s engineers to understand what needed to happen, and shared our knowledge and experience with them to find a solution. This allowed them choices in their design process.

All during this time we kept the focus on the fact that this would be a coil cord eventually. We finalized the cable design, extruded the cable and then set about making the coil cords. Early on the issue wasn’t creating the cable, for us that was fairly easy. The bigger issue was making this complex of a cable into a retractable cable; a retractable cable solution that worked inside a one-inch pipe. During the cable design phase, we constantly made sure our customer knew the choices, and impacts of, stranding, conductors, insulation materials, shielding options, jacketing materials and construction methods.  Doing this allowed us to balance the electronic performance and the mechanical performance. The final cable had an OD of only 0.291 inches, and when turned into a coil cord did in fact work inside the pipe.  A solution was found! Meridian Cable can design cables as complex as this, simpler and more complex too, and we would welcome sharing what we know with you.  We have engineers that are happy to talk about wire and cable all day long. Your cables are unique; your vendor’s solutions should match.

Custom Coiled cords: An uplifting story

Last December Meridian Cable sales rep Emily Mierzejewski received an urgent request from a product designer for assistance in developing and producing a UL-certified coil cord prototype. The designer needed the coil cord prototype in place for an April product launch of a new line of power-free, height-adjustable workspace furniture. The coil cord was an integral part of the furniture design. This meant development, production and coil cord delivery had to be expedited.

Custom coil cord design is usually a collaborative effort between customers and Meridian engineers. A customer details project specifications and then Meridian engineers work with them to produce a technical drawing of the coil cord, as well as desired plugs and connectors. The drawings detail cable gauge, diameter, coating material, etc.

In this case, the customer already had a technical drawing of the coil cord needed as part of the larger furniture design, so Meridian engineers only had to review the drawing and ensure its feasibility. “The cable cord needed for this project was actually fairly big,” explains Mierzejewski. “The customer knew he needed a sturdy cable cord with a certain amount of resistance.” During the specification process, the engineers also suggested some alternate connectors that would be more effective within the design and more cost efficient.

In the interest of time, the customer decided to forego the customary practice of getting a few prototype samples upfront and asked for an initial small run instead. So Meridian built a mold, extruded the cable and fitted the coil cord with the required connectors. Then each coil cord was tested and inspected for quality. Delivery of the finished coil cords arrived just in time to be fitted into the furniture before their commercial debut.

About Coiled Cords

Coiled cords are straight cables with curly sections incorporated within them. Typically used as an alternative to straight cables, cable cords are used in situations where a compact cord with the ability to expand and retract is needed. Coil cords offer the flexibility to fit into smaller spaces without becoming tangled or knotted.

About Meridian Cable LLC

Meridian Cable LLC is a custom cable assembly and coiled cords manufacturer, specializing in engineering and design work for custom applications. Meridian Cable extrudes its own cable and can provide completed cable assemblies according to customer requirements. Meridian Cable is based in St. Augustine, Fla., where it will soon have a U.S. manufacturing facility. Currently Meridian Cable manufactures in Tianjin, China. For more information, please visit www.meridiancable.com or call 1-866-866-0544.

Molded Cables: What You Need To Know

Molded Cables: The Facts

Molded cables are extremely important but are rarely noticed by those using them. According to Meridian Cable’s owner and resident molded cable assemblies expert Bud Kinzalow, though they can be small, these cables serve large and important purposes.

Molded cables derive their name from the fact that plastic is typically molded onto cable, and their purpose is to mechanically attach connectors to cables. Kinzalow notes that custom molded cables are created through a specialized process that allows for maximum protection of important parts. “First,” he says, “the connectors are attached to the cable and are subsequently placed into a mold. Next, the mold is closed and the plastic is injected into the cavity that surrounds the cable terminal or connector interface.”

What results from this process are quality molded cables that can stand the test of time. Kinzalow adds, “People use these protective molded cables every day when they grip the plastic on their headphone jacks, plug something into the computer or plug a power cable into the wall.” Created to protect the connection between wires and connectors, molded cables have become ubiquitous not only in the wire and cable industry but also in everyday life. People are able to charge their computers, listen to music and perform other everyday tasks thanks to molded cable assemblies.

Molded Cables: Typical Uses

One purpose that custom molded cables serve is protection of connectors and cables from the elements. According to Kinzalow, “In years past- and still sometimes today – many connections between wires and connectors were soldered, meaning they were welded at a low temperature and one metal was used to hold together two other dissimilar metals. The resulting soldered connection often needed to be covered so that water, other pieces of metal or environmental elements couldn’t damage or short the connection between the wire and the connector. The over-molding was likely created to provide this protection and ensure a longer lifespan for the soldered cable.”

These days, molded cables are rendered to fit varying types of connectors and serve many different purposes. These numerous everyday uses emphasize the importance, in today’s technologically advanced world, of molded cables. You can find molded cables in:

  • Stereos
  • Headphones
  • Computer chargers
  • Cell phone chargers
  • Power cords
  • USB cables
  • Many more everyday devices

Molded Cables: Who Makes Them?

Since molded cables have so many uses, there are numerous manufacturers that can create them to suit varying situations. These manufacturers may turn to custom cable assembly companies like Meridian Cable to design and create custom molded cables for them.

“Original Equipment Manufacturers (OEMs) looking to design and sell molded cables should ensure that the vendor that they turn to is UL, ISO, FDA and even military cage code certified,” Kinzalow advises. For example, if an OEM turns to Meridian Cable to build custom molded cables, they will find that Kinzalow’s company has all the necessary certifications in addition to the design expertise to be able to create a design that is unique to each OEM’s performance specifications. “Also important,” he adds, “is having the manufacturing wherewithal to make the product that the customer needs, the logistics capability to deliver the molded cables anywhere in the world, and the integrity to follow through on what was promised.”

It is extremely important to trust the vendor who is designing and making the cables because, though these molded cables can be small and seemingly easy to make, there is in fact a great deal of work that goes into creating perfectly fitted and useful molded cables.

Molded Cables: Who To Contact

If you are an Original Equipment Manufacturer looking for custom molded cables, contact Meridian Cable (www.meridiancable.com) for service from a UL approved manufacturing facility and UL approved distributor of over 50 different types of wire and cable. Meridian Cable is also ISO 9001:2008, cage code and FDA certified. Call us at 1-866-866-0544 to speak with one of our designers and discuss how we can meet your performance specifications for custom molded cable assemblies or view some of our molded component designs.