CiA402 drives

Add a CiA402 EtherCAT drive to your configuration and link it to the application.

  7 minute read  

This page adds a CiA402CiA 402 is the CANopen device profile for servo drives and motion control, published by CAN in Automation. It defines how a drive behaves on the bus: its state machine, its modes of operation such as CSP, CSV and CST, and standard objects like the control word (0x6040). Over EtherCAT the profile is used through CANopen over EtherCAT (CoE). drive to the EtherCAT configuration and links it to your Motorcortex application. The examples use a Synapticon SOMANET drive and an Elmo Gold drive. It takes three parts; click one to jump to it.

Part 1: get the ESI file that matches the drive firmware 1 Get the ESI file Matching the firmware Part 2: add the drive in the ECAT tool 2 Add the drive Scan, ESI file, PDOs Part 3: link the drive to the application 3 Link it Production, simulation

How the drive connects

The drive exchanges data with the EtherCAT master through its PDOs. The rxPDO carries what the drive receives, such as targets and the control word; the txPDO carries what it sends back, such as actual values and the status word. Links in the EtherCAT configuration connect those PDO entries to parameters of the Motorcortex application.

Motorcortex application How to link the drive to the application Links EtherCAT configuration The CiA402 drive and its PDOs CiA402 drive rxPDO and txPDO rxPDO txPDO To the drive Control word · Mode of operation · Target position · Target torque · Torque offset From the drive Status word · Mode of operation display · Position actual value · Torque actual value

The PDO entries shown are those of the Elmo example below. Your application may need others.

Before you start

  • The robot application is deployed on your controller: see Deploy an application.
  • You know how to open and use the ECAT tool: see Add a device.
  • You have the ESI file for your drive. It must match the drive’s firmware version. Drive manufacturers supply ESI files on request or through their own tools.
Not sure which firmware your drive runs? Read it from the drive

Log in to the controller over SSH, then:

  1. List the devices on the bus:

    ethercat slaves

    0  0:0  PREOP  +  EK1914, 2 Ch. Safety Input/Output 24V,  TwinSAFE
1  0:1  PREOP  +  EL6910, TwinSAFE PLC
2  0:2  PREOP  +  EK1110 EtherCAT-Verlängerung
3  0:3  PREOP  +  SOMANET CiA402 Drive
4  0:4  PREOP  +  0x0000009a:0x00030924

    In this example the SOMANET drive is at position 3 and the Elmo drive at position 4. Run ethercat slaves --help for the meaning of each column.

  2. Find the SDO that holds the software version. Search the SDO list of the drive at position 3:

    ethercat -p3 sdos | grep -i software

    SDO 0x100a, "Manufacture Software Version"
  0x100a:00, r-r-r-, string, 264 bit, "Manufacture Software Version"
SDO 0x607d, "Software Position limit"

    Repeat with -p4 for the second drive.

  3. Read the version from 0x100a:00:

    ethercat upload -p3 0x100a 0:0
ethercat upload -p4 0x100a 0:0

    The example drives return:

    • Elmo: Twitter 01.01.16.00 08Mar2020B01G
    • SOMANET: v5.0.3-16-g58c2f1c06

  4. Check that this version matches your ESI file.

Add the drive in the ECAT tool

  1. Open the ECAT tool and check your connection.

  2. Press + Add your first devices.

  3. On the From Scan tab, press Scan Bus, select the drives, then press Add Devices.

    Add Devices dialog, From Scan tab: Scan Bus found five devices, including the SOMANET drive at position 3 and an unnamed drive at position 4

  4. Load the ESI file: select the drive, press next to the device name, choose ESI file and select the .xml file. This works the same for every EtherCAT device.

    SOMANET CiA402 Drive after loading its ESI file: the device menu with ESI file highlighted, and the rxPDO tab listing RxPDO Mapping 1 (0x1600)

  5. Check the PDOs. Every entry your application needs must be in an rxPDO or txPDO, see the table below. What this takes depends on the drive:

Entry CiA402 object Direction Needed
Controlword 0x6040 rxPDO Always
Modes of operation 0x6060 rxPDO Always
Target position 0x607A rxPDO For CSP
Target velocity 0x60FF rxPDO For CSV
Target torque 0x6071 rxPDO For CST
Torque offset 0x60B2 rxPDO Optional: a torque feedforward in CSP and CSV
Statusword 0x6041 txPDO Always
Position actual value 0x6064 txPDO Always
Velocity actual value 0x606C txPDO Recommended
Torque actual value 0x6077 txPDO Recommended

The standard robot configuration maps all three targets, so the drive mode can change without a new PDO mapping. It also links a torque sensor entry, a vendor-specific object, for the sensor torque transformation.


Synapticon SOMANET

The SOMANET ESI file comes with its PDOs already mapped, so there is usually nothing to add. In the example above, RxPDO Mapping 1 (0x1600) holds the controlword, modes of operation and the three targets, and the txPDO holds the statusword and the actual values.

  1. Open the rxPDO tab and check that every rxPDO entry from the table is there.
  2. Do the same on the txPDO tab.
  3. If an entry is missing, add it to a PDO as shown in the Elmo tab.

The SOMANET drive also offers a TorqueSensor entry in its txPDO. The standard robot configuration links it to …/sensorTorqueActual.


Elmo Gold

The Elmo ESI file offers many PDOs, most of them pre-configured with fixed entries. Use the freely configurable rxPDO 0x1607 and txPDO 0x1A07 instead, and add the entries from the table yourself.

  1. On the rxPDO 0x1607, press and choose Add Entry.

    PDO menu of the empty rxPDO 0x1607 with Add Entry highlighted

  2. Add every rxPDO entry your application needs. This example is for CSP with a torque offset:

    rxPDO 0x1607 with target position, control word, mode of operation, target torque and torque offset

  3. Do the same on the txPDO 0x1A07:

    txPDO 0x1A07 with position actual value, status word, mode of operation display and torque actual value

Other drives

Every vendor sets up its ESI file differently. There are two kinds:

  • Already mapped, like the Synapticon: the PDOs come with their entries. Check that every entry from the table is there.
  • Fill it yourself, like the Elmo: pick a configurable rxPDO and txPDO, and add the entries as shown in the Elmo tab.

The drive’s manual says which PDOs can be changed and how many entries each can hold. Map only the entries you need: every entry adds to the data sent each cycle.

The application only receives and sends drive data through links. Each drive entry can carry two: a production link to the application, which is always connected, and a simulation link to the simulator, which only counts while the drive is simulated. This is one axis of the standard robot configuration; paths starting with …/ are under root/AxesControl/actuatorControlLoops/actuatorControlLoopNN/, where NN is the axis number.

Production link always connected Drive entry Simulation link only when simulated rxPDO: to the drive DriveLogic/driveControlWord 6040:00Controlword handled by the simulated drive DriveLogic/driveOpMode 6060:00Modes of operation handled by the simulated drive …/motorPositionTarget 607A:00Target position Simulator/targetPosition …/motorVelocityTarget 60FF:00Target velocity Simulator/targetVelocity …/motorTorqueTarget 6071:00Target torque Simulator/targetTorque …/motorTorqueOffsetTarget 60B2:00Torque offset Simulator/targetTorqueOffsetavailable, not linked by default txPDO: from the drive DriveLogic/driveStatusWord 6041:00Statusword handled by the simulated drive …/motorPositionActual 6064:00Position actual value Simulator/positionValue …/motorVelocityActual 606C:00Velocity actual value Simulator/velocityValue …/motorTorqueActual 6077:00Torque actual value Simulator/torqueValue …/sensorTorqueActual vendor-specificTorque sensor Production link: always connected Simulation link: only when the device is simulated
  1. In the ECAT tool, open the drive’s rxPDO and txPDO tabs and add a production link to each entry, as on the left of the map. Use the axis number in actuatorControlLoopNN. Array parameters, such as DriveLogic/driveOpMode, take the axis number minus one as the channel.
  2. To run without the drive, add the simulation links on the right as well. Open each simulation link’s properties with and switch Simulation on; the turns blue.
  3. On the drive’s Settings tab, link Link Simulation to root/DriveLogic/driveSimulation with the drive’s channel, so the drive logic simulates the drive too.

Next: Step 2: set the drive mode of operation.