asp_servo_api

EtherCat servo API utilizing the SOEM ethercat master

Prerequisistes and dependencies

sudo apt install build-essential cmake

tinysml2

git clone https://github.com/pjensfelt/tinyxml2.git
cd tinyxml2
mkdir build
cd build
cmake ..
make
sudo make install

SOEM

git clone https://github.com/pjensfelt/SOEM.git
cd SOEM
mkdir build
cd build
cmake ..
make
sudo make install

Test the installation by running for example slaveinfo which should give you an output like this if you have no slaves attached

patric@PJMSI:~$ slaveinfo 
SOEM (Simple Open EtherCAT Master)
Slaveinfo
Usage: slaveinfo ifname [options]
ifname = eth0 for example
Options :
 -sdo : print SDO info
 -map : print mapping
Available adapters
Description : lo, Device to use for wpcap: lo
Description : enp3s0, Device to use for wpcap: enp3s0
Description : wlo1, Device to use for wpcap: wlo1
End program

Update LD_LIBRARY_PATH

If you get errors like slaveinfo: error while loading shared libraries: libsoem.so: cannot open shared object file: No such file or directory you need to tell Linux where to find the newly installed libraries

sudo ldconfig

Installation instructions

git clone https://github.com/pjensfelt/asp_servo_api.git
cd asp_servo_api
mkdir build
cd build
cmake ..
make
sudo make install

How to use

There should be an XML file describing the system configuration (see for example)

<?xml version="1.0" encoding="utf-8"?>
<SystemConfiguration>
    <EthernetPort></EthernetPort>
    <CycleTime_ms></CycleTime_ms>
    <ServoCollection>
       <Servo position="" name="">
          <Type></Type>
          <StartupParameters>
            <!-- Items -->                        
          </StartupParameters>
          <PDOmapping>
            <Tx>
              <!-- Objects -->
            </Tx>
            <Rx>
              <!-- Objects -->
            </Rx>
          </PDOmapping>
       </Servo>
       <!-- More servos -->
    </ServoCollection>
</SystemConfiguration>

An object is as defined in the manual, e.g.:

<Object>
   <Name>Position</Name>
   <Index>0x6064</Index>
   <Subindex>0</Subindex>
   <Type>INT32</Type>
</Object>

The name is used when writing to and reading from the servo.

servo_collection.write(servo_name,"Position",target_position);

Be sure to use the correct data type for the target value.

In the StartupParameters tag of the XML file, an object is combined with a value to form an Item:

<Item>
   <Object>
      <Name>Mode of Operation</Name>
      <Index>0x6060</Index>
      <Subindex>0</Subindex>
      <Type>INT8</Type>
   </Object>
   <Value>10</Value>
</Item>