Threaded Communication and Networking library

Overview

A library to communicate to devices connected through CAN, EtherCat, USB or TCP/IP.

License

The source code is released under the MIT license.

Authors: Philipp Leemann, Christian Gehring, Remo Diethelm

Dependencies

Common

message_logger

Ethercat

soem_rsl

Usage

See tcan_example for an easy example how to use tcan library. tcan has two modes: synchronous and asynchronous:

In asynchronous mode, the library creates three threads for each bus: a thread that handles incoming CAN messages, one that sends outgoing CAN messages and one that checks if devices/SDOs have timed out (sanityCheck).
In synchronous mode, it is up to the user to call the BusManagers readMessagesSynchronous(), writeMessagesSynchronous() and sanityCheckSynchronous() functions in his main loop.

To prevent overflow of the output buffer of the SocketCAN driver (which is used by the SocketBus class) there are two possible approaches:

Set the output queue length to a value which is large enough to hold the messages of one cycle: sudo ip link set can0 txqueuelen 100
Setting the SocketBusOptions::sndBufLength_ to 1 (or any other small value > 0). This sets the socket buffer size to its minimal value and will make the socket blocking if this buffer is full (which is NOT the same as the buffer of the underlying netdevice)

Setting up the interface

Virtual can interface

Use the vcan.sh script provided in tcan_utils/bash:

#!bash

rosrun tcan_utils vcan.sh {start|stop|restart} <name>

e.g.

#!bash

rosrun tcan_utils vcan.sh start can0

CAN-USB Adapter

Use the canusb.sh script provided in tcan_utils/bash:

#!bash

rosrun tcan_utils canusb.sh {start|stop|restart} [<dev>] <name> [<can_rate>]

e.g.:

#!bash

rosrun tcan_utils canusb.sh start /dev/ttyUSB0 can0 -s8

rosrun tcan_utils canusb.sh stop can0

where -s8 sets the can baud rate according to the following table:

flag	bitrate
-s0	10kbit
-s1	20Kbit
-s2	50Kbit
-s3	100Kbit
-s4	125Kbit
-s5	250Kbit
-s6	500Kbit
-s7	800Kbit
-s8	1Mbit

Peak PCIe card

The linux kernel >= 2.6.25 supports Socketcan natively. To setup the interface, you can use

#!bash

sudo ip link set can0 type can bitrate 1000000 berr-reporting on
sudo ip link set can0 up

However the performance of the standard linux kernel driver may be bad (large gaps between can frames). Peak provides their own Socketcan driver, which can be downloaded from http://www.peak-system.com/fileadmin/media/linux/index.htm. Unpack the archive and install it with

#!bash

make clean
make -C driver NET=NETDEV_SUPPORT
sudo make install

The driver can be uninstalled with

#!bash

sudo make uninstall

To set the baudrate, the above ip command cannot be used, do the following instead:

#!bash

echo "i 0x001C" > /dev/pcan0

where 0x001C is a hex representation of the baudrate, which can be taken from the following table:

hex	bitrate
0x7F7F	5kbit
0x672F	10kbit
0x532F	20Kbit
0x472F	50Kbit
0x432F	100Kbit
0x031C	125Kbit
0x011C	250Kbit
0x001C	500Kbit
0x0014	1Mbit

vzhr/tcan