Data traffic with cyclic process data

The user can create one set of process data with an arbitrary structure, max. 1280 bytes. This data set can be written cyclically in its entirety to the module or read by it. Individual access to the constituent parts of this data set is not possible (keyword: addressing). Control is performed by the task by means of a handshake via Control/Status Word, so that several task cycles may be necessary for saving or reading back, depending on the extent of the data and the cycle time.

When the module is switched on, the regularly saved data from the last operating session is offered immediately via the inputs for reading in.

Commissioning: the cyclic process image must be created identically at inputs and outputs, max. 1280 bytes. The creation is done via the dialog "Insert Variable". Open the dialog box by right-clicking on Inputs/Outputs -> selecting "Add New Item...".

Data traffic with cyclic process data 1: — Manual creation of the cyclic process data

If the input and output have different sizes, the module start fails: "PREOP to SAFEOP failed".
If more than 1280 bytes are created, the module start fails with "Invalid SM In/Out Cfg".

The data to be written in the EtherCAT plug-in module EJ6080 is output to the module by the task at the outputs.
The last valid data received by the EtherCAT plug-in module EJ6080 as read data arrives at the task at the inputs with no further assistance.

	Structure of the process data in TwinCAT 2.10 The structure of the input/output data is subject to the following restriction up to TwinCAT 2.10 build 1330: All defined variables must consist of n*bytes, single bits or such compound structures are not allowed. If such data is defined, the EJ6080 attains the OP state, but reports an error due to Working Counter = 1.

Examples:

Data traffic with cyclic process data 3: — Permissible configuration using the EL6080 as an example

Data traffic with cyclic process data 4: — Impermissible configuration using EL6080 to TwinCAT b2.10 b1330 as an example

Cyclic operation with handshake, recommended operating sequence:

Output the input data to the module; set ControlWord = 1.
Once the module has successfully adopted the data, StatusWord = 1 is returned.
Set ControlWord = 0.
Wait until StatusWord = 0 is returned; the module is then ready for a new write access operation.

Data traffic with cyclic process data 5: — Cyclic operation with handshake

Typical example of a measurement for a cyclic write process according to the sequence described above (Beckhoff reserves the right to make unannounced amendments):

20 bytes: 200 µs
1250 bytes: 2.5 ms

	Process data image and frame length In the case of short cycle times, an extensive process image for the EtherCAT plug-in module EJ6080 can result in an Ethernet frame that is longer than the cycle time. Therefore, in order to use the entire 1280 bytes of the cyclic process image, the cycle time must be at least >= 200 µs.