EtherCat

Basic information about EtherCAT

Physically, the network is connected with junctions and branches, as you're used to with ordinary Ethernet. In terms of traffic, however, communication is always serial. All data to and from all nodes passes through every node. You can therefore think of the cable as a ring, where one wire pair is for the outgoing direction and the other for the return. The return pair carries information from all nodes back to the master, which is why EtherCAT communicates extremely fast between master and nodes, often using a single telegram.

Because of this principle, a break in the return pair or a loose contact on any connector or cable will often affect the whole network. So follow the manual carefully when it comes to cable type, length, shielding, grounding and routing.

If you disconnect a node, the electronics will often handle it by ignoring the node. This is not the case with a loose contact or noise, which is seen as a disturbance and a LostFrame. LostFrames cause an EtherCAT error and can make communication stop.

EtherCAT is therefore somewhat more vulnerable than, for example, EtherNet/IP, where data traffic between the nodes and the master is more individual, often with one telegram in each direction per node. That principle limits performance, speed and capacity, but makes it more robust against faults on a cable or connector.

How to add a node to EtherCAT

1. Have you installed the product's ESI file in Sysmac Studio? The latest version of Sysmac Studio comes with ESI files for all relevant Omron products preinstalled. Go to step 5.
2. If this is not an Omron product, you need to add the ESI file (.xml). A smart trick is to run Compare and Merge to find the revision number:
   
   The revision number is the code after the last colon. This number MUST match the ESI file you install, otherwise you will run into trouble.
   Select Display ESI Library from the right-click menu on the CPU after selecting EtherCAT, and click Install (File).
   Check that the file does not have a red dot, which indicates that something is wrong. If it's OK, go to step 4.
3. Click + to see if you can find the error yourself. If not, contact Omron Support. If an ESI file has errors or is missing information, we may have to charge for running tests for you. We are not allowed to modify ESI files that are not ours.
4. Restart Sysmac Studio.
5. Drag and drop the correct product from the menu on the right onto the master or the network. Alternatively, you can scan the network with Compare and Merge with Actual Network Configuration from the master's right-click menu.
6. Edit PDO if necessary.
7. Transfer to the controller and test.
8. If you have communication problems, see the solution about Troubleshooting EtherCAT .

Useful function blocks for EtherCAT

You can find useful function blocks for EtherCAT in the EEF Library.

EtherCAT ring

RX2, Q2A and Q2V SI-ES3 EtherCAT can be used in an EtherCAT ring. MX2 cannot be used in a ring, "due to technical design". JC06 cannot form a ring, even though it looks like it in the documentation and on the module itself. This marking is probably meant for masters that need 2 cables to form a ring. Important settings when using an EtherCAT ring Consecutive Communications Error Detection Count for the nodes is set to 2 or more. For 1S this is parameter 2200.00. PDO communications timeout detection count for the master is set to 3 or more.

Predefined system variables in Sysmac Studio for EtherCAT