Quick start

1. Mounting

Install the EL3255 as described in section Mounting and wiring.

Connect 1 - 5 potentiometers according to the pin assignment.

2. Configuration

Create a configuration in the TwinCAT System Manager by manually inserting the terminal or scanning it online. Refer to installation chapter TwinCAT 2.x regarding this.

EtherCAT XML Device Description If the XML description of the EL3255 is not available in your system you can download the latest XML file from the download area of the Beckhoff website and install it according to the installation instructions.

3. Online operation

Activate the EtherCAT master and start the terminal in OP state. In the input variables the EL3255 must deliver State=OP (8) and WC=0.

4. Delivery state

The terminal behaves as follows in the delivery state or after scanning in the System Manager:

• 5 channels active
• 10 kOhm potentiometer (CoE setting 0x80n0:1C)
• Distributed Clocks deactivated, frame-triggered operation
• Filter deactivated
• Vendor calibration active

This results in a conversion time of typically 500 µs across all channels.

• Process data status + value for each channel
  

• CoE settings (in this case channel 1: index x80n0, where n=0)

5. Distributed Clocks mode

If you wish to use Distributed Clocks mode, change the process data and the mode of operation accordingly.

Since the EL3255 is a device for input data, "DC-Synchron (input based)" is recommended.

The scanning of the potentiometers is then cyclically initiated by the DC-Sync signal; hence, synchronized operation with other DC-capable terminals can take place.

Distributed Clocks and filters The activation of the filters is not permissible in Distributed Clocks mode.

Process data

Via the PDO selection, 5 - 1 channels can be selected as PDOs to be cyclically transmitted (A). The deactivation of a channel reduces the size of the process image; the corresponding Error LED then no longer has any function.

CoE parameters

The CoE parameters can now be changed for each channel in the CoE.

Parameterization via the CoE list (CAN over EtherCAT) The terminal is parameterized via the CoE - Online tab (double-click on the respective object) or via the Process Data tab (allocation of PDOs). Please note the following general CoE information when using/manipulating the CoE parameters: - Keep a startup list if components have to be replaced - Differentiation between online/offline dictionary, existence of current XML description - Use "CoE reload" for resetting changes

The following settings should be made in each channel

1. Nominal resistance of connected potentiometer

The electrical measuring range encompasses potentiometers from 300 Ω to 50 kΩ. An internal correction function improves the measuring accuracy by linearization if the connected potentiometer is known to the terminal.
Therefore the load resistance is to be set in the CoE x80n0:1c. The setting closest to the actual value is to be selected.

Note on open-circuit recognition from firmware 04 The open-circuit recognition runs acyclically in the background. The open-circuit recognition for the potentiometer wiper takes place every 3 cycles, if the value 10k (0) is entered in all 0x80n0:1C objects (on all channels). In this case the open-circuit recognition is particularly fast. If a >20 kOhm potentiometer is nevertheless connected to one of the channels, a broken wire message may occur, even if no broken wire is present. Therefore, the nearest suitable value that matches the connected potentiometer should be set in 0x80n0:1C. The open-circuit recognition for the wiper is slower, if at least for one channel a value  >10k ( > 0) has been entered.

2. Filter setting

The filter setting from channel 1 is simultaneously effective for all channels.
A combination of Distributed Clock mode and filter activation is not permissible.

With the exception of the filter setting, different values can be specified for each channel.

The settings can also be loaded via the SPS/PLC/Task at runtime, e.g. using function blocks from TcEtherCAT.lib.

7. Diagnostics

Both the terminal and each individual channel signal their proper function in status variables, see Process data.

For proper operation the cyclic evaluation of the following information is recommended:

• Device EL3255
• WorkingCounter WcState
  must be 0 in each cycle, otherwise no valid data acceptance has taken place.
• Status State
  The EC status of the terminal must be in OP mode, i.e. the 3^rd bit is set. There must not be any error.
• per channel
• Error, Underrange, Overrange
  These variables must be 0/FALSE.
• SyncError
  This variable indicates a synchronization error in DC mode and must be 0/FALSE.
• TxPDO State
  This variable indicates an internal process data error and must be 0/FALSE.
• TxPDO Toggle
  This variable indicates the delivery of new data by changing its value.

8. Operation

During operation the potentiometers/sensors are cyclically measured and the process value is transmitted to the master.