The Controller Area
Network (CAN or CAN-Bus) has been invented for use in
vehicles (cars, trucks) to reduce the complexity of the
cabling systems and to allow the control of different
sensors and devices. Because of its reliability against
noise and transmission errors the CAN-Bus is also used as an
industrial "Fieldbus". Today CAN-Bus is mainly used to
control factory automation for many different controlling
and data acquisition applications.
CAN-Bus is a broadcast bus with differential serial data
transmission, where the bits are
send in NRZ coded
frames. The frames consist of an ID to identify the sender
type and up to 8 data bytes,
the frames are
sensed from all CAN-bus nodes. A CAN network can be
configured to work with two different frame formats: the
standard frame format has an
11Bits ID (CAN 2.0A) whereas the extended frame format uses
29Bits ID (CAN
2.0B). CAN-Bus features an automatic 'arbitration free'
A CAN message that
is transmitted with highest priority will 'win' the
arbitration, and the node transmitting the lower priority
message will sense this, back off and wait.
Using the VScom CAN adapters a PC can be connected to the
CAN Network in a simple manner: over USB, over a serial port
or over Ethernet. All VScom CAN adapters support both CAN
2.0A and CAN 2.0B frame format to fulfil the task of
controlling and monitoring. The PC can in the same time
used to log the data and status of the CAN-bus,
without interfering with the control application.
The CAN adapters also support CANFestival, an
Open Source CANopen Framework. CANopen is a CAN-based higher
layer protocol that is used in various application fields,
such as medical equipment, offroad vehicles, maritime
electronics, railway applications or building automation.
CANopen unburdens the developer from dealing with
CAN-specific details such as bit-timing and
implementation-specific functions. It provides standardized
communication objects for real-time data, configuration data
as well as network management data.
CANHacker, a tool for analyzing and transmitting frames on
the CAN BUS, is included in the product package.
The NET-CAN adapters are connected to a PC
via Fast Ethernet and support data speeds up to up to
1MBit/s over the CAN Network. The drivers for Windows
operating systems install a virtual serial port (Com Port).
This COM Port is then used by the software to transfer data
and commands to the CAN-bus. Hardware-based automatic flow
control of the COM Port ensures the reliable data
transmission, i.e. no data losses, to/from CAN bus.
Additionally to the Driver Mode with virtual serial ports
the NET-CAN may operate via Raw TCP. Since the flow control
is performed inside the NET-CAN, even in this mode the
transmission is reliable. Raw TCP may be used by any
operating system, not only Windows.
Because the drivers basically emulate a serial COM port, the
users may use a terminal program for data transmission and
control. The binary data of CAN bus are converted to an
ASCII-format, they are sent in this form. The same
ASCII-format is available on Raw TCP, so instead of a serial
terminal program an application like Telnet performs the
same tasks for users. This modus may be used manually, to
simply test the equipment in the installation phase. Also
dedicated customer applications can use the terminal mode.
However this is an effort, which is not necessary to be done.
Instead the customer applications can use the supplied CAN
frame library (a DLL in Windows), which automatically packs
the application data and commands into the CAN bus frame
data format for send, receive and control/status commands.
Using the CAN frame library the user can focus on his real
application, and don't care about the frame data formats.
The CAN Frame library is developed to be compatible with
future VScom CAN products.
The USB-CAN adapters are
connected to a PC via USB 2.0 and support data speeds up to
up to 1MBit/s over the CAN Network. Also USB 1.1 with the
Full Speed data rate of 12Mbit/s is sufficient to operate
this device. Therefore even older computers are suitable for
The drivers for Windows operating systems install a virtual
serial port (Com Port).
This COM Port is used in the same way as the
virtual serial port with NET-CAN, providing all the same
Also under Linux OS drivers emulate a serial port, with
secure flow control as well.
The power supply of USB-CAN is provided via
the USB port, which results in minimum cabling. The low
power consumption is an additional advantage.
The SER-CAN adapter is similar with the
USB-CAN adapter, but it is connected directly to an RS232
serial port of any computer. The SER-CAN adapter has the
same specifications concerning CAN bus interface and
operates the serial port in the same way as USB-CAN. The
SER-CAN adapter uses the same CAN frame library as interface
for native CAN frame format. The RS232 interface limits the
maximum data speed on the serial port side, but the adapter
can be configured to filter frames based on certain
information, so it only accepts the matching data. This
feature, optionally combined with suitable higher level
protocols, can significantly reduce the required data
throughput. Further the SER-CAN uses RTS/CTS flow control to
guarantee the error free data transmission.
The SER-CAN is powered by an 5V DC external
power adapter. A suitable wall-plug adapter is part of the
All adapters are available
a very attractive price.