3th-Party Controller and transmission timing of the EtherCAT frames different to the Lenze system: sporadically occurring torque peaks (fixed from V01.04.01)
Corrected from:
Servo inverter i950 FW: fromV01.04.01.1417
Response of the new version:
The time behaviour within the i950 Servo Inverter and the interpolation function in the event of a telegram failure have now been further optimised. The effects of torque peaks on the machine when timing problems occur during setpoint transmission are now significantly reduced.
Important: For operation of the i950 under a controller from another manufacturer, a minimum time interval between the cycles of master and slaves is still required. Detailed information can be found under 'Short-term measures' and illustrative graphics in the attached presentation.
What happens?
Sporadically occurring torque peaks, which may be noticeable by audible cracking noises on the running machine.
When does the behaviour occur?
Operation of the i950 Servo Inverter (CiA or CiA-Advanced) under a controller from another manufacturer, e.g. a Beckhoff controller and
In the Beckhoff controller, the SYNC shift time (definition of the frame transmission time in the master) is deliberately set to a particularly small value, deviating from the default.
The problem does not occur under the following circumstances:
Lenze system: Use of a Lenze controller. The timing of the setpoint transmission of a Beckhoff controller is different from the Lenze system.
Beckhoff controller: Retention of the default setting of SYNC shift time = 30% in the Beckhoff controller (master).
For operation of the i950 (CiA or CiA-Advanced) under a controller from another manufacture, a minimum time interval of 100 µs is required, which is defined as follows:
time interval between the transmission time of the EtherCAT frame in the master (defined by the 'SYNC shift time' in the master) and
the start time of the control cycles in the slaves (determined by the SYNC0 shift time in the slaves).
This minimum time interval ensures that the i950 has enough time before the start of its control cycle to receive the EtherCAT frame, accept the contained set values and convert them.
the SYNC shift time in the master control is set too small, the i950 may not be able to accept the setpoints because the new setpoints may not arrive in time. It is also possible that dropouts occur only sporadically due to time jitter.
There are two ways to set the minimum time interval:
Master shift (setting of the SYNC shift time in the master): Shifting the frame transmission time in theEtherCat master to an earlier time. For a Beckhoff control the value of 'SYNC Shift Time' has to be increased. Thus, the SYNC time in the master (frame transmission time) is brought forward compared to the SYNC0 time in the slaves (the EtherCAT frame is transmitted earlier).
With this variant it is necessary to check whether this has an effect on other EtherCAT devices, because now all EtherCAT devices receive the sent frame earlier.
Slave shift (setting of the SYNC0 time for all slaves):
Shifting the SYNC0 time for the slaves to a later time. This also shifts the start of the control cycle in the drive controllers i950 (slaves).
This variant is not expected to have any effect on other EtherCAT devices.
Slave shift: Determine the time shift to be set in the slaves:
EtherCAT frame timing, determine existing time difference: i950, parameter 0x2E00:16 (time difference in µs between end of EtherCat frame and next SYNC0 in the i950). Hint: Parameter 0x2E00:16 is subject to a certain range of variation. It is therefore recommended to observe this value over a longer period of time (use the trend function if necessary). The smaller the value, the less favourable. The recorded time difference should be at least 100 µs over the entire period.
Adaptation of the SYNC0 shift time for the slaves: An adaptation of the SYNC0 shift time is only necessary if the smallest measured value 0x2E00:16 is less than 100 µs. If yes, then adjust the SYNC0 shift time as follows: SYNC0 shift time = (current value) + (100 µs) - (smallest value 0x2E00:16)
The SYNC0 shift time for the slaves is usually set via the EtherCAT master or the operating tool of the controller that functions as the EtherCat master, e.g. Beckhoff TwinCAT.
