Trying to lay out a wiring project that involves several different systems and an ECU can look like an immensely difficult task on paper, however, if you use modern technology it can actually be easier than you think. Adding products that use a CAN bus-style connection will make getting all of your wiring done in a clean and simple fashion while adding plenty of additional benefits.
When you begin researching all of the different ECUs, data acquisition devices, and digital dashes on the market you will see they mostly use a CAN-style connection. CAN stands for Controller Area Network and it was developed by Bosch in the 1980s as a way to make the connection between controllers and sensors simpler. The basic idea behind a CAN is to allow different parts to communicate with each other without wiring every individual component together.
Lawson Mollica from AEM Electronics explains the advantages CAN bus connections are able to provide by making wiring less complex by sending data across just two twisted wires.
“CAN simplifies the way multiple controllers (or ECUs) can be connected together and communicate with one another. It delivers a bunch of advantages in any application, but especially for the racer. The most obvious is weight savings. Less wiring means less weight, and shared data means fewer redundant sensors. It also means less cost, since the data from a single transducer can be sent to multiple devices, and additional wiring and ancillaries to control electrical load are not necessary. Because the way the data is transmitted is standardized, it makes it much easier to diagnose errors and also configure communications across multiple controllers, as well as translate the raw data into something most of us can understand. It can stand up to EMI (electromagnetic interference), and it’s easily expandable.”
So how does a CAN system actually work and allow everything to communicate? It all comes down to sending packets of data from one device to another via a standardized method. Lawson is able to break this down in a way that any racer can understand.
“CAN messages are sent using what are called bit identifiers, which are a series of numbers that define the message type. Depending on the CAN standard, these come across in either 11 or 29 bits, but regardless, each identifier uniquely identifies the message packet. There are some great resources online that get really in-depth on this topic, but to keep it simple and relevant to racing the identifier consists of an announcement of the message, the relevance of the message, and the amount of data in the message,” Lawson explains.
Now that you’re armed with the knowledge of what a CAN bus system is, it’s time to see how you can use it to help streamline the wiring of your racecar. Keeping things simple during the wiring process provides several different benefits, not the last of which is allowing you to keep unwanted weight out of a racecar and make identifying problems easier.
“Along with simplicity, another benefit is the diagnostic channels that are available when using CAN. Take for instance, the AEM Inline AFR Sensor Controller: while you can connect it using a 0-5V analog output to an ECU or logger, if you use the available CAN connection, the message will not simply be the current AFR value. The CAN output contains real-time diagnostic channels as well as operating status channels and even if the system is using the internal resistor for calibration or a free air calibration. The other cool thing about it is that the AFR data that is placed on the CAN bus can be read by multiple devices at the same time. So, if your standalone ECU is CAN enabled, it can receive the data and use if for engine control, and if you have a separate dash or logger they can also receive the same CAN data simultaneously, removing the requirement for multiple sensors measuring the same thing, just so different controllers can see it, as well,” Lawson says.
Having the benefit of being able to expand your systems as needed is another advantage that CAN bus connections can provide. The CAN connections make it simple to start adding or changing how you wire everything if you need to make adjustments to any system on your racecar.
“Imagine you have a standalone ECU with limited analog, digital and frequency inputs. Once you use them up, there is no way to add more. However, if that ECU accepts CAN, then you can add virtually unlimited channels to the ECU through the bus. For example, if you are using an Infinity 708 ECU and you want to add eight channels of AFR, you could add them by integrating two AEM Four Channel Wideband UEGO Controllers over a single two-wire connection into the Infinity’s CAN input,” Lawson explains.
After you’ve got all of the sensors in your system talking to the ECU via CAN you’ll need a way to monitor what’s going on while in the driver’s seat. That’s where adding a digital dash becomes important, and CAN connections are a part of ensuring the dash can hear what all the systems are saying.
“A CAN-based CD Carbon Digital Dash is a great addition for all of the reasons stated above. If you have a CAN-based ECU or CAN-based controller module, then you don’t need to wire any sensors to it to get the data you need into the dash, and in the case of CD Carbon digital dashes, you can mix and match devices from different manufacturers. This means you can get hundreds of channels of data into the dash, and while you may not want to see all of that data on the screen, you can log it in one place and analyze all of the data from one log using AEMdata analysis software, which we provide for free,” Lawson says.
Getting different ECUs to communicate with different dashes is possible when a CAN-based style product is being used. A CAN connection doesn’t know what brand the device is that it’s connected to…it only facilitates the transfer of data.
“If you have a Haltech Elite 2500 or Holley HP ECU, MoTeC PDM15 Power Distribution Module, AEM 22 Channel CAN Sensor Module and RaceGrade 8 Channel EGT Module, you can send the data from all of these devices to the CD Carbon Dash to see whatever channels you want across four main switchable pages, set warnings and alarms for any and all channels. You also can log them all in one device with the logged data available to be analyzed in a single synchronized data log, and still have the ability to add more devices and collect more data over CAN in the future. With more than a thousand channels available within the CD Carbon Dash, you have the very real ability to take control of your data, and that’s what makes the integration of CAN so awesome, especially in a racecar,” Lawson explains.
Now that you have a better understanding of what a CAN connection is and how it works you’ll be able to pick the best devices for your vehicle. Having the ability to acquire more data is possible when using devices that all have CAN-based connectivity.