Why is it so important to specify FMS when ordering a vehicle? What is J1939 and how does it relate to FMS? What solutions are available for integration of buses without FMS, or inadequately specified FMS? Should you store all data you can get your hands on?
There are several benefits to gain from having an FMS integration in place. This means that you can monitor vehicle parameters remotely and distribute the FMS parameters to different applications within the vehicle as well. To get access to the parameters and to distribute them is quite easy, as long as you request an FMS interface when purchasing the bus, and also order FMS with the right specifications, which you can read more about here. It is VERY IMPORTANT to order an FMS and specify the order carefully, because once the bus is delivered, it is much more difficult to access the information.
The FMS protocol based on J1939, defined by the manufacturers, is a very good foundation. Any information that is available in the FMS or the J1939 can be presented, but it is much easier and straightforward to get the information through the FMS. The limitations of the system does not lie in the possibility for an integration solution to present and use the information, but what information is accessible preferably through FMS, but also to extract from the J1939. If you can’t get the information out of the system, you can’t use it, simply put.
J1939 vs FMS
J1939 is a standardized communication protocol that many bus manufacturers adhere to, and that contains about a thousand different information parameters regarding the bus. This protocol is a read-write protocol which means that it is sensitive to disturbance. If you connect equipment to the J1939 that disturbs the information flow, you risk disturbing the vehicle functions and, worst case scenario, cause the vehicle to stop.
FMS was developed to help third-parties to get vehicle information in a standardized way. FMS is a read-only communication protocol with a standardized connection, making it possible to get the information streams you are interested of, without risk of disturbing the function of the bus. It is very important not to impact the function of the vehicle, by affecting the bus communication protocol. Otherwise the bus might malfunction and the warranty be void. The FMS has a built-in barrier to prevent anything you do with the FMS from impacting the bus functions.
The FMS comes in four versions, the latest Bus-FMS, version 4, contains about 70 different parameters, while the J1939 contains several thousands . The FMS is in most cases a subset of the J1939, except for the Telltales, which typically are a part of FMS, but not a part of J1939.
Useful parameters you might want specified in the FMS are engine coolant temperature, oil pressure, odometer, gear and engine speed. Note that oil pressure is not part of the standard FMS-specification. It must be requested as an addition from the manufacturer.
Different vehicle manufacturers supply different information through FMS as a standard, which makes it imperative to be specific when ordering FMS. In some cases it is even worse. In different models from the same vehicle manufacturer, you will get different info through the FMS. Sometimes there are even differences between vehicles within the same model. This depends on who “programmed” the CAN network and who put things together (often engineering sub-suppliers). The standardized FMS connector might not be used by all vehicle manufacturers, so you might want to include that into the FMS specification as well.
Solutions without FMS
If the FMS specification isn’t implemented before the new vehicle is delivered, the situation can become quite complicated, depending on which make and model of the vehicle.
In many cases, when the bus manufacturer uses the J1939 communication protocol, it is possible to get the information out of the system with the help of CAN-Crocodiles. A CAN-Crocodile is an inductive connection that doesn’t affect the information flow. They aren’t very expensive, so this is often a viable solution to the problems occurring when the FMS isn’t ordered or properly specified.
You can find more information about the CAN crocodiles here.
The CAN-Crocodile solution works well for many vehicles, but for some manufacturers, like Mercedes, using proprietary protocols instead of J1939, the solution isn’t that straight forward. Then the situation is getting even more complicated. However, you might be able to use a Squarell solution. Squarell is a Dutch company, specializing in solving and converting proprietary data to FMS data. It is more expensive, but to get some much needed information out of the system it is many times well worth it. Read more on their website; squarell.com
What information should you extract and why? The first reaction might be that you want to send all the information up in the cloud, to have access for statistics or other reasons, but in most cases that isn’t advisable. The information soon becomes too bulky when you collect too many parameters too often. Normally you would aim to limit what information you collect. Be smart now, instead of later being forced to decide which of all the non-processed raw data you collected, to get rid of, since your server space equals Facebook or Google in size.
Be specific, and set the information collection interval to fit the task. For example, you might want a narrow interval for the Odometer, to know that the bus is moving, but for example engine speed is pointless to transmit too often, since the information will be old when it reaches the back office anyway. The door opening is a good parameter, indicating that the vehicle is at a bus-stop, but it doesn’t have to be transmitted too frequent, since the process spans over some time. Some parameters, you can also obtain in more than one way. For example, vehicle speed, you can get either through the FMS or with the help of GPS.
The two most important parameters to make sure they are in the FMS specification, are oil pressure and cooler water temperature. For electrical vehicles, battery level is interesting as well.
So, to conclude. When ordering a new vehicle, DO NOT FORGET to order FMS and to specify the FMS. To know what you want is key here, so a suggestion would be to contact a supplier of open ITxPT standard vehicle solutions for assistance in getting the FMS specifications right for your present operation as well as for the future.
Disclaimer: The content of this blog post is the author’s opinion and doesn’t reflect the opinion of any other person or organisation.