Changeover of process data sets

The process data to be transmitted (PDO, ProcessDataObjects) can be selected by the user

completely for all channels via the selection dialog “Predefined PDO Assignment” (all TwinCAT versions)
selectively for individual PDOs, taking into account the excluded elements.

“Predefined PDO Assignment” selection dialog (from TwinCAT 2.11 build 1544 onwards)

Defined PDO sets can be preselected if they exist in the XML description.

Changeover of process data sets 1: — Predefined PDO assignments of the EL3002-0000-0017

As a result, all channels of the EL30xx are set at the same time to standard or compact process image.

Selective PDO selection

All TwinCAT versions support the selective selection of individual PDOs, as defined in the XML description.
Exclusion criteria prevent irregular combinations.

Changeover of process data sets 2: — Selective PDO selection

Explanatory notes for Fig. Selective PDO selection: In the “Process Data” tab, it can be seen under (A) that this EL3002 offers several different PDOs for the transmission, and in fact for each channel

“AI Standard” from the CoE index 0x1A00/0x1A02: Measured value and status of the channel , therefore 4 bytes
and
“AI Compact” under CoE index 0x1A01/0x1A03: only the measured value of the channel, therefore 2 bytes

By selecting the necessary Input SyncManager in (B), the PDO assignment under (C) can be carried out manually. The process data can then be linked in the TwinCAT tree (D).

Note about earlier EL30xx versions

EtherCAT Terminals of version EL30xx-0000-0016 (FW < 04) only offer element-wise linking according to Fig. Element-orientated process data in EL30xx-0000-0016.

Changeover of process data sets 3: — Element-orientated process data of the EL30xx-0000-0016

An update of the XML description to Rev. -0017 is possible.

Note about the 1-byte status of earlier EtherCAT terminals

Previous analog input terminals from Beckhoff (e.g. EL31x2) had a Status byte instead of the Status word that is now implemented and therefore a 3-byte interface. 8 additional bits now offer extended diagnostic options, wherein the default process image of the EL30xx and EL31xx now encompasses 4 bytes, Status word and Value word. The bit meanings of the LowByte are retained; Limit1 and Limit2 as 2-bit types are shown in the case of the EL30xx.

Changeover of process data sets 4: — 3-byte interface of the EL31x2

If the 3-byte interface for linking to the analogue input channel is implemented in existing PLC projects, the TwinCAT System Manager nevertheless offers the possibility to link the EL30xx/EL31xx with a 4-byte interface.

To do this, open the link dialog as usual by double-clicking on the variable and activate the AllTypes checkbox. As a result, variables with differing sizes are also offered for linking. Select the corresponding 1-byte input variable for your application. In the following SizeMismatch dialog the cover of 8 bits is confirmed. Fig. Connecting 4-byte interface of the EL31xx/EL30xx to a 3-byte interface existing in the project.

Changeover of process data sets 5: — Connecting the 4-byte interface of the EL31xx/EL30xx to a 3-byte interface existing in the project

Note about TwinCAT 2.10

The structured representation of the EL30xx from revision EL30xx-0000-0017 onwards as shown in figure (B) below is due to a corresponding interpretation of the designations of the variables. This function does not exist in TwinCAT 2.10 (A) yet, which is why only element-wise linking is possible there.

Changeover of process data sets 6: — Element-orientated process image under TwinCAT 2.10 – structured representation TwinCAT 2.11