A rugged tablet in an excavator, tractor or truck is often meant to show more than an app: engine speed, operating hours or fault codes from the vehicle. For that, the device has to talk to the vehicle. It does so over the CAN bus, on commercial vehicles usually in the SAE J1939 variant. In our range, four RuggON devices list a CAN port in their datasheet: the Viking II 07A, the Vortex 07X, the Vulcan 10A and the Vulcan 10X. This article first explains how the CAN bus and J1939 are built, then what a terminal in the vehicle has to offer, and finally what the four datasheets document and what they leave open. Form factor, vehicle power supply and mounting are covered in Vehicle-mount computer and forklift terminal. Here the subject is only the data connection.
Bosch began developing the CAN bus (Controller Area Network) in 1983 and presented the protocol officially in 1986. The ISO 11898 series of standards describes it in several parts: part 1 defines the data link layer and the signalling, part 2 the high-speed physical layer. In the vehicle, the bus consists of two twisted wires, CAN_H and CAN_L. Data is sent as a voltage difference between the two wires.
There is no master. Any control unit may send as soon as the bus is free. If two start at the same time, the message with the lower identifier wins and the other waits, without any data being lost. A message is called a frame. In classic CAN it carries up to 8 bytes of payload and has an identifier of 11 bits or, in the extended format, 29 bits.
In classic CAN the bit rate is up to 1 Mbit/s and it determines the length of the network. According to Wikipedia, the network stays below 40 m at 1 Mbit/s, while 500 m is possible at 125 kbit/s. A termination resistor of 120 Ω sits at each end of the cable.
CAN governs the transmission, but not what is in the 8 bytes. On commercial vehicles that is defined by SAE J1939, a recommended practice of SAE International for communication and diagnostics between vehicle components. J1939 runs on CAN, uses the 29-bit identifier and relies on ISO 11898 for the physical layer. The identifier is divided into 3 bits of priority, 18 bits of Parameter Group Number (PGN) and 8 bits of source address.
A PGN names a message that bundles several measured values. Each value inside it is called a Suspect Parameter Number (SPN) and is defined by start bit, length, scaling factor, offset and unit. CSS Electronics works through an example: the message EEC1 has the PGN 61444 (hexadecimal F004) and contains the engine speed. The raw value 4968 with the factor 0.125 gives a speed of 621 rpm.
The usual bit rate is 250 kbit/s; 500 kbit/s was added with J1939-14. Control units receive their 8-bit source address dynamically at start-up (address claiming). Messages longer than 8 bytes, such as diagnostic messages with fault codes (DM1), are split into packets by a transport protocol. It carries up to 1785 bytes, which is 255 packets of 7 bytes each. For diagnostics on the vehicle, CSS Electronics names a 9-pin Deutsch connector according to J1939-13.
J1939 is widespread in trucks and buses, and also in agricultural, forestry and construction machinery and on ships. ISO 11783 (ISOBUS) for agricultural machinery and NMEA 2000 for ships use the same protocol core as J1939. Vehicles in transport and in forestry and agriculture may therefore speak J1939.
Bosch published the first version of CAN FD (Flexible Data-Rate) in 2012. It is described in ISO 11898-1:2015. A frame carries up to 64 instead of 8 bytes, and the data phase may run at a higher bit rate than the arbitration. ISO 11898-2:2016 defines bit timing for CAN FD up to 2 and up to 5 Mbit/s. J1939 on CAN FD is described in J1939-17 and J1939-22, which CSS Electronics dates to 2020 and 2021.
For your selection this means: the entry CAN bus in a datasheet does not say whether CAN FD is meant. Of the four devices, only the Vortex 07X names Dual CAN FD, and there as an option.
The structure raises questions that you should settle before buying.
Whether the vehicle manufacturer permits a connection to the bus, and whether the terminal may only listen or also send, is decided by the vehicle manufacturer. The device datasheet says nothing about it.
The table follows the core data tables of the RobustBook datasheets, which are based on the manufacturer datasheets from RuggON.
| Device | Display | CAN according to datasheet | Operating temperature | Weight |
|---|---|---|---|---|
| RuggON Viking II 07A | 7 inches | CAN bus, optional SAE J1939 × 1 | -30 °C to +60 °C | 1.25 kg |
| RuggON Vortex 07X | 7 inches | CAN bus × 2; optional Dual CAN FD / SAE J1939 × 1 | Atom x7211E: -30 °C to 60 °C; Core i5-1335UE: -30 °C to 55 °C | 1.67 kg |
| RuggON Vulcan 10A | 10.4 inches | CAN bus 2.0B / SAE J1939 × 1 | -30 °C to 60 °C | 3.2 kg |
| RuggON Vulcan 10X | 10.4 inches | Optional: CAN bus 2.0B × 2 or SAE J1939 × 1 | -30 °C to +55 °C | 3.2 kg |
The Vulcan 10A lists the CAN port in its datasheet without the word optional: one port for CAN bus 2.0B or SAE J1939. In the configurator on the product page, CAN bus 2.0B and SAE J1939 still appear as selectable interfaces. Clarify the version before you order. The device runs Android 14.
On the Vulcan 10X, CAN is an option, namely an interface module with either two ports for CAN bus 2.0B or one for SAE J1939. The device runs Windows IoT Enterprise.
At 7 inches and 1.25 kg, the Viking II 07A is the lightest of the four devices and runs Android. Its datasheet names one CAN port and SAE J1939 as an option. The Vortex 07X also has 7 inches and runs Windows 11 IoT Enterprise. It is the only one of the four with two CAN bus ports without the word optional. In the manufacturer's layout, one sits on each of the groups IO-B (generic connector) and IO-C (M12 connector).
The datasheet of the Fieldbook N101 lists no CAN port. CAN appears there only in the signal list of the expansion slot; the page says nothing about protocol, bit rate or connector.
None of the four manufacturer datasheets gives a bit rate, a connector pinout, a termination resistor or a software interface for CAN. So ask before ordering: Which bit rates does the port support? How is it wired, and which connector fits? Can a termination resistor be switched in? Which drivers or programming interface exist for Android or Windows? May the device also send messages?
What no device datasheet answers is which PGNs and SPNs your vehicle sends. That is in the documentation of the vehicle or engine manufacturer. J1939 reserves the PGN range 00FF00 to 00FFFF (hexadecimal) for manufacturer-specific messages. A terminal that supports J1939 will therefore not automatically read every value of your machine.
Besides CAN, all four devices have serial interfaces, including RS-232 and RS-485. How the serial standards differ is explained in RS-485, RS-422 and RS-232 compared.
Only if it is meant to read vehicle data. For applications without a vehicle link, such as order handling or navigation, it is not needed. Without a port on the device you would need an additional intermediate device; whether one works with the tablet in question, you ask the manufacturer. In our range, four RuggON devices list a CAN port in their datasheet.
No. CAN describes the transmission; J1939 defines what is in the frames on top of it: priority, PGN, source address, the assignment of measured values and diagnostics. A device with a CAN port reads J1939 only if its software also evaluates the protocol.
No. CSS Electronics lists OBD2 as a separate CAN-based protocol next to J1939. Some commercial vehicles have a type B OBD2 connector on which J1939 is available at pins 6 and 14. Which connector your vehicle has is stated in its documentation.
The datasheet of the Vulcan 10A names CAN bus 2.0B / SAE J1939 in one port. On the Vulcan 10X and the Viking II 07A, SAE J1939 is named as an option, on the Vortex 07X as part of the option Dual CAN FD / SAE J1939. Choose the version before you order.
For J1939 in a truck or construction machine with room for 10.4 inches, the Vulcan 10A (Android) and the Vulcan 10X (Windows) come into question. On the 10X you order the CAN option as well. If installation space is tight, the Viking II 07A fits with 7 inches and 1.25 kg. The Vortex 07X is the choice if you need Windows, two CAN ports or CAN FD.
Not covered is a tablet in a dock that is meant to read vehicle data. For the other models, including all Durabook and Getac devices, the datasheets name no CAN port; a connection would have to be clarified with the manufacturer and is not documented here. What remains open in every case is whether your vehicle manufacturer releases the connection and which messages it sends. Settle protocol, bit rate and connector on the vehicle first.
Tell us the vehicle, the protocol (CAN 2.0B, J1939 or CAN FD) and the bit rate, and the RobustBook team will help you choose the right version.