原网页：Create a simple EtherCAT IO network (Implementation Notes)

PS：文章最后给了一个知网连接，是在ROS下使用Ethercat的相关论文。

1. 硬件设置（例子）

1. T61 联想笔记本 (带 Ethernet 卡)
2. IO rack: EtherCAT Couper, 8 DI, & 8DO (all Beckhoff)

2. Beckhoff（倍福） EtherCAT 驱动

1. 安装ROS的OROCOS toolchain
2. 安装Simple Open EtherCAT Master (soem)库

git clone https://github.com/orocos/rtt_soem.git

3. 运行catkin_make，编译连接soem
4. 将Ethercat设备连接到以太网口。EtherCAT可通过标准以太网工作。直接建立连接，连接应该不能通过交换机，因为典型的以太网耦合器没有IP地址。
   （原文：Connect EtherCAT device to ethernet port. EtherCAT works over standard ethernet cable. Make a direct connection, I do not think connections through switches work since EtherCAT couplers do not have IP addresses (typcially)）
5. 在 soem_core 包中给 slaveinfo 访问socket命令的root访问权限：

sudo setcap cap_net_raw+ep bin/slaveinfo

（可能需要安装这个：）
sudo apt-get install libcap2-bin

6. 执行 slaveinfo 模块：

rosrun soem_core slaveinfo <device, typcially eth0>

模块成功执行时，将会打印一张连接到的从机列表。
7.（最新版的soem中可能不需要这一步）soem堆栈有一个BUG，无法识别未知模块的IO大小。 以下补丁修复了该BUG（已提交BUG）。

 diff --git a/soem_master/soem_master_component.cpp b/soem_master/soem_master_component.cpp
 index e166ad0..dc6b460 100644
 --- a/soem_master/soem_master_component.cpp
 +++ b/soem_master/soem_master_component.cpp
 @@ -79,6 +79,8 @@ bool SoemMasterComponent::configureHook()
              // wait for all slaves to reach PRE_OP state
              ec_statecheck(0, EC_STATE_PRE_OP, EC_TIMEOUTSTATE);

 +          ec_config(FALSE, &m_IOmap);
 +
              for (int i = 1; i <= ec_slavecount; i++)
              {
                  SoemDriver
 @@ -89,6 +91,8 @@ bool SoemMasterComponent::configureHook()
                      m_drivers.push_back(driver);
                      log(Info) << "Created driver for " << ec_slave[i].name
                              << ", with address " << ec_slave[i].configadr
 +                            << ", output bits " << ec_slave[i].Obits
 +                            << ", input bits " << ec_slave[i].Ibits
                              << endlog();
                      //Adding driver's services to master component
                      this->provides()->addService(driver->provides());

8. 在soem_master目录下运行rosmake编译补丁。
9. 编辑 test.ops 脚本，启动master并将OROCOS消息映射到ROS主题。

 import("soem_beckhoff_drivers")
 loadComponent("Master","soem_master::SoemMasterComponent")
 Master.displayAvailableDrivers()

 # Default nic is eth0, set if different. e.g.
 #Master.ifname = "eth1"

 # Crawls the network and identifies attached devices.  Devices are loaded
 # (if a driver exists) and given names "Slave_1***".  The *** appear to be
 # the module order (at least this is the case for a single rack)
 Master.configure()

 # Setting the update period (in seconds).  This determines the rate at which
 # the data is published on the ROS side (setting this value to zero turns
 # off updating
 Master.setPeriod(0.05)

 # This stars the Master "task" running.  It will update at the period set
 # above
 Master.start()

 # This command remaps OROCOS topics to ROS topics
 stream("Master.Slave_1002.bits", ros.topic("DI"))
 stream("Master.Slave_1003.bits", ros.topic("DO"))

10. 在 ocl 包中给 deployer-gnulinux 访问socket命令的root访问权限：

 sudo setcap cap_net_raw+ep bin/deployer-gnulinux

11. 在命令行中 launch the master：

 roslaunch soem_master soem_master_test.launch

launch文件会launch orocos，load test.ops脚本。

3. 其他

1. 打开OROCOS消息日志：export ORO_LOGLEVEL=5</tt> （见 [The Orocos Component Builder's Manual - Logging]。(http://www.orocos.org/stable/documentation/rtt/v2.x/doc-xml/orocos-components-manual.html#corelib-logging)）
2. OROCOS消息和ROS消息的转换（见 rtt_ros_integration_example）例程脚本：stream("Master.Slave_1002.bits", ros.topic("DI_bits"))

译者注：

这有一篇关于ROS下使用Ethercat的文章：ROS下基于Ethercat的串联机器人控制系统