No sync-controlled process data acceptance of CAN1_IO

What happens?
The process data received via the CAN1_IO channel of the CANonboard interface (X4) is not always accepted in a sync-controlled way. This may result in sudden step changes in torque when transferring a position master value.

When does the problem occur?
The function restriction may occur in multi-axis networks synchronised via CAN.

Which products are affected?
EVS93xx-EI (Servo PLC V8.0 and lower)
EVS93xx-ET (Servo PLC V8.0 and lower with technology function)
ECSxA V8.3 and lower
EPL-10200 (Drive PLC V8.2 and lower)

Possible diagnostics?
None.

Short-term measures/recommendations?
The sync-controlled acceptance of the process data received via CAN1_IO depends on the sync cycle time (C1121) and the runtime of the PLC task which calculates the setpoint.

In order to avoid this function restriction the following conditions are to be adhered to due to specific system requirements:

    Sync phase (C1122) < Sync cycle time (C1121) – 350µs

In case of the CAN_bSyncInsideWindow_b system variable the following is to be observed when parameter telegrams (SDO) and process data (PDO) are transmitted at the same time:

    Sync window (C1123) = 10µs + 8 bytes SDO runtime

With a baud rate of 500kBaud the SDO runtime is approx. 240µs.

Evaluation:
Depending on the parameterised sync cycle time it may happen taht in case of a strong task utilisation the process data received via the CAN1_IO channel are not accepted in a sync-controlled way. In this case the PLC application uses the data from the CAN telegram received before. Depending on the data transmitted this may for instance lead to sudden step changes in torque.

URL for linking this AKB article: https://www.lenze.com/en-de/go/akb/201104230/1/