AKD2G EtherCAT W7011 Warning and F7011 Fault Synchronization Error Support

Foreword

Prior to troubleshooting synchronization warnings or faults it is important to note the following.

When using the ESI file with TwinCAT3 for example, the sample period is set in the Startup SDO list for the drive in TwinCAT3. If the EtherCAT cycle time is changed in the master then the Startup SDO list should be edited as well so on startup of the EtherCAT master the drive's sample period matches the EtherCAT master.

W7011 (Warning)

Historically when the EtherCAT timing was determined to be incorrect by the AKD2G drive’s synchronization monitoring, it would result in a warning in the drive/axis indicated by the LCD display or in Workbench as W7011. In this case the warning could be defeated or ignored.

For users with older firmware, from an operational perspective, W7011 will not prevent you from getting into OP, but it means the control signals are behind at least some of the time. If it’s always behind, then there will be some delay in the motor’s position command, but it will move smoothly. If it’s sometimes on time and sometimes behind, this may exhibit as noise on the motor. You may hear clicking and observe the position jumping depending on how severe the issue is.

In this case it requires shifting where the EtherCAT packet occurs relative to sync0 either via the master (preferred) or via the drive.

F7011 (Fault)

For EtherCAT compliance, per the firmware release notes, the warning (W7011) was changed to a fault (F7011) beginning in firmware 02-10-02-000 and later.

The official position is the drive is providing the user with an indication the EtherCAT timing isn’t correct and should be remedied instead of ignored.

The Fault description is as follows. 

Per the F7011 entry, it is possible to switch the supervision off ( and defeat the fault occurrence ) by setting ECAT.MAXSYNCERROR to a value of 0 using either 10F1h sub 2 in the EtherCAT startup list or by Workbench Terminal. Note the fault entry states it is not recommended.

F7011 - What does it indicate or mean?

Essentially W7011 means there is too much jitter and/or there is an issue with the EtherCAT timing where generally cyclic events occur earlier in the bus cycle than they should.

For example, if the SM2 Event from the master comes before the send out of Tx-PDO (SM3).

The EtherCAT Master sets the timing of the SM2 event relative to Sync0.

The events need to be in the order of: Sync0 – Position loop interrupt – TxPDO – RxPDO (SM2) – next Sync0.

To aid in a better understanding of possible scenarios of incorrect EtherCAT timing, a Powerpoint presentation is offered as a supplement to this application note.

CAN Emergency messages for W7011 and F7011 in the master

Sometimes the issue is first observed in the EtherCAT master either in the Error Code objects (see below) and/or received as a CAN Emergency message.

Objects 0x603F and 0x683F hold the last error for Axis 1 and Axis 2 respectively.

• Error Code 0x878C was the warning W7011 in firmware prior to 02-10-02-000.
• Error Code 0x878E is the fault F7011 in firmware beginning in 02-10-02-000 and later.

Resolving EtherCAT timing issues

As previously stated the events in the EtherCAT cycle need to be in the order of: Sync0 – Position loop interrupt – TxPDO – RxPDO (SM2) – next Sync0.

To correct the EtherCAT timing issue (and cycle event timing, the adjustments that can be made are:

• Rx shift offset in the master (SM2 shift offset).
• ECAT.INPUTSHIFTU and ECAT.PLLOFFSET in the drive.

Some issues we’ve seen are when the customer can’t set the RxPDO (SM2) shift offset in the master, and/or when the master has so much jitter that the RxPDO (SM2) timing jumps around such that it occurs before the Tx or after the next Sync0.

In some cases adjusting ECAT.INPUTSHIFTU and ECAT.PLLOFFSET in the drive wasn’t enough to resolve the timing issues. Additionally, the SM2 shift offset in the master for each drive along the network chain had to be adjusted. The first drive needs little or no shift. The last drive needs the most shift. It all depends on how much delay there is in each device when transferring data through the device onto the next device. And it also depends on how many EtherCAT devices there are on the network. The EtherCAT cycle rate is also a factor. For example, 1 or 2 ms is a long enough cycle time that you normally won’t see sync issues. But running at 250us doesn’t give much room for error.

The AKD2G Web Help provides details on synchronization and also how to use the Workbench scope as a tool to diagnose and remedy EtherCAT timing issues.

From the AKD2G Help:

Synchronization (kollmorgen.com)

As aforementioned, the help has details on capturing the timing using Workbench Scope which can help troubleshoot the issue. For example, here’s the timing captured in the Workbench Scope.

The following are additional parameters to check in Workbench Terminal and provide a report of.

For the AKD2G EtherCAT Troubleshooting List navigate to the following support page.The document provides a list of information and data needed to provide Technical Support related to AKD2G EtherCAT issues.

AKD2G EtherCAT and CANopen Landing Page | Kollmorgen