Fault management

General

Fatal errors are error types requiring reinitialization of the connected AX5000 feedback systems. This requires a change in communication state of the EtherCAT State Machine from Operational (Op) to ErrorSafe-Operational (ErrSafe-Op), which takes place automatically. ErrSafe-Op is a special case of Safe-Op. Two-channel devices only have one communication unit, which means that both channels are disabled. In this particular case, the change from Op to ErrSafe-Op results in the working counter of the SyncUnit becoming invalid, since the AX5000 can no longer supply valid actual values, resulting in all servo drives in this SyncUnit being disabled.

Requirement

The measures described in this section assume the following software versions.

• TwinCAT v2.10 b1329 or later versions
• Firmware v1.05 b0009 or later versions

Special features for two-channel devices

By default, a fatal error totally disables a two-channel device, including the error-free channel. If such a behavior is not permitted in the application, the default behavior can be changed with the following parameterization of IDN P0-0350.

P-0-0350: Change of communication state in the event of fatal errors

0: Immediate state change (default)

If the servo drive is in “Op” state when the fatal error occurs, it immediately changes from “Op” to “ErrSafe-Op” and sets the error bit in the EtherCAT state.

1: No change in communication state while the other channel is enabled

In this case the AX5000 initiates the state change from Op to ErrSafe-Op in the event of a fatal error on one channel only once the error-free channel has been deactivated. The error-free channel can therefore continue to operate until it is deactivated.

PLC

The IDN P-0-0040 is used to be able to diagnose in the PLC whether a fatal error situation has occurred that will lead to a state change next time the channel is deactivated. This IDN should be read acyclically in the PLC with block “FB_SoERead”. Cyclic evaluation is not meaningful, since the AX5000 no longer supplies valid inputs in ErrSafe-Op state after a fatal error, and therefore no valid information is transferred cyclically.

xxxx00: Both channels are error-free.

xxxx01: The other channel has a fatal error. As soon as this channel is deactivated, the communication state changes from “Op” to “ErrSafe-Op”.

xxx1x: This channel has a fatal error. As soon as the other channel is deactivated, the communication state changes from “Op” to “ErrSafe-Op”. An error reset is not possible.

SyncUnit diagnostics

The individual servo drives should be consolidated in meaningful groups, depending on the application. Each of these groups is allocated to a SyncUnit. Since each group has its own working counter, the individual groups can continue to operate independently in the event of fatal errors. For particularly critical applications, each AX5000 can be allocated a separate Sync Unit. However, this step should only be implemented in cases where it is required, because each further Sync Unit results in additional data traffic on the EtherCAT strand.

Allocation of servo drives to a Sync Unit

Start the TwinCAT System Manager and left click on the associated EtherCAT strand (1). Select the “EtherCAT” tab (2) and left click on “Sync Unit Assignment” (3). The “Sync Unit Assignment” submenu appears. Section (4) shows the servo drives and their allocation to the Sync Units. Servo drives AX5203 and AX5118 belong to Sync Unit “Cycle Process”, 5206 belongs to Sync Unit “Transport”.

Reinitialization, troubleshooting and reset

1. Analyse and rectify the fatal error.
2. Carry out an error reset via IDN S-0-0099. To this end the blocks “FB_SoEReset” or “FB_SoEReset_ByDriveRef” are available in the PLC.
3. Automatic change of communication state from “ErrSafe-Op” to “Op”.
4. NC axis reset. To this end the block “NC_Reset” is available in the PLC.

Re 3.

For the communication state to automatically switch back to “Op”, flag “Wait for WcState is OK” must be activated on the corresponding AX5000. This is automatically the case for new configurations. In existing configurations, it may have to be set accordingly.
Start the TwinCAT System Manager and left click on the associated servo drive (1). Select the “EtherCAT” tab (2) and left click on “Advanced Settings....” (3). The “Advanced Settings” submenu appears. Select the flag “Wait for WcState is OK” with the left mouse button (4).