Application - brief overview
The EL2252 must be used based on the following procedure:
- Determining the current distributed clock time in 64 bit format, e.g. through the active SysTime of the EL2252
- Calculation of the required StartTime (output time) with 64-bit-operations
- process data transfer:
- In the following cycle set Activate = 3; this activates the start time in the terminal
The EL2252 now waits as described above until the start time occurs and then send the output data to the power stage
Until the switching event occurs, Activate and the output bits Output/ Tristate must be maintained in accordance with the target state
In the event of a voltage loss in the terminal the start time is lost and must be set again by the controller
Therefore, only one switching event can be defined for each EL2252, which affects all 4 output variables Output and Tristate of channel 1 and 2 at the same time. For each EtherCAT cycle only one switching event can be defined.
Once a switching task has been issued it cannot be cancelled. However, since a switching task that has already been issued can always be overwritten by a new one. Switching tasks that have already been issued can effectively be cancelled through overwriting with an invalid switching task (e.g. time in the past).
The selectable PDO "Feedback" can be used to check the success of the switching task output. It maps the connected outputs bit by bit, and the tristate circuit in a byte:
- Bit 0: Output channel 1
- Bit 1: Tristate channel 1
- Bit 2: Output channel 2
- Bit 3: Tristate channel 2