Commissioning instructions

EtherCAT cycle time

If the EL500x is operated faster than the time required for SSI communication and processing, the start of the next SSI communication is no longer synchronous with the EtherCAT bus cycle and the local DC signal, but is delayed until the next free signal or until processing is completed.

The minimum meaningful cycle time depends on the firmware version. Typical data can be found in the following table, although they may have to be verified for specific applications depending on the frame length and inhibit time.

Model

Typical minimum recommended cycle time

EL5001 up to FW10

400 µs

EL5002, EL5001 from FW11

200 µs

TxPDOToggle from the extended status word can be used to determine the actual update frequency in the application.

Commissioning

Default setting: 25 bit, Gray coding, 500 kbaud, no PowerFail bit.

On commissioning the following parameters must be set:
• Settings according to CoE
• DC mode
• Process data

CoE settings

The terminal is parameterized via the CoE – Online tab (double-click on the respective object) or via the Process Data tab (assignment of PDOs).

Depending on the firmware version/terminal type the EL500x settings must be implemented in CoE range 0x4066 and following or range 0x8010.

Commissioning instructions 1:

EtherCAT XML Device Description

The display matches that of the CoE objects from the EtherCAT XML Device Description. We recommend downloading the latest XML file from the download area of the Beckhoff website and installing it according to installation instructions.

Commissioning instructions 2:

Parameterization via the CoE list (CAN over EtherCAT)

The EtherCAT device 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 notes 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

In TwinCAT 2.11 the online CoE list is structured as follows:

Commissioning instructions 3:
CoE settings and EL500x process data in TwinCAT 2.11

SSI settings

The total size of the data depends on the encoder used. It is also type-specific whether a power-fail bit or another auxiliary bit is supported. The counter value 0x6010:11 "Counter Value" is determined on the basis of the value entered in the index 0x80n0:12 "SSI data length".
A few example configurations are shown below:

Specification of the
encoder

Settings in the CoE of the EL500x

ST

MT

Error bit

0x8010:0F
SSI-frame type

0x8010:11 SSI-frame size

0x8010:12 SSI-data length

0x8010:02
Enable power failure bit

13

0

0

1: Single-turn analysis is active

13

13

0: Power failure bit is not active

12

12

1

0: Multi-turn analysis is active

25

24

1: Power failure bit is active

12

12

0

2: Variable analysis is active

24

24

0: Power failure bit is not active

13

12

0

2: Variable analysis is active

25

25

0: Power failure bit is not active

16

16

0

2: Variable analysis is active

32

32

0: Power failure bit is not active

16

0

0

2: Variable analysis is active

16

16

0: Power failure bit is not active

13

16

1

2: Variable analysis is active

30

29

1: Power failure bit is active

12

12

2

2: Variable analysis is active

26*

26*

0: Power failure bit is not active

*) Analysis of the data and division into position and auxiliary bits must take place in the PLC

If the encoder offers more than one additional bit, this can be done by appropriate configuration in index 0x80n0:11 "SSI-frame size" and 0x80n0:12 "SSI-data length". The maximum size of 32 bits must be considered here. If the parameters are of the same size, then not only the position, but also the auxiliary bits are displayed in "Counter Value". Analysis of the data and division into position and auxiliary bits must take place in the PLC.

If the settings are not made correctly in the CoE, or if there is an error at the inputs, this is indicated via the status bits:

Data Error
(Index 0x60n0:01)

Frame error
(Index 0x60n0:02)

Possible error type

TRUE

FALSE

Error at the SSI input:

  • SSI without power supply
  • Wire break at the SSI data inputs D+ or D-

If no data transmission takes place the SSI input of the terminal is on low level.

FALSE

TRUE

There is an incorrect data frame, the data frame was not terminated with zero, or possibly

  • Wire break in the clock lines
  • Incorrect parameterization in the CoE

TRUE

TRUE

  • Wire break at the SSI data inputs D+ or D-
  • Data cables swapped

FALSE

FALSE

If bits in the counter value are shifted despite correct CoE parameterization, this may be due to swapped clock lines.

EL5001: n = 1 for channel 1
EL5002: n = 0 for channel 1, n = 1 for channel 2

Commissioning instructions 4:

Velocity calculation from the position data

If a velocity or acceleration value is to be determined from the returned position value, it is recommended to use the DC mode for time synchronization.

Distributed Clocks (DC)

In distributed clock mode the SSI communication is not started with the arrival of the EtherCAT frame, but by the SYNC signal of the slave, which is synchronized via all DC-capable devices in the EtherCAT system. In this way a DC synchronization precision of 100 ns between devices can be achieved. Through further processing in the EL500x the actual start of the SSI communication achieves an accuracy of < ±500 ns relative to the ideal synchronous time.

For more information on the DC system, refer to the Basic EtherCAT documentation.

The minimum EtherCAT cycle time recommendations also apply in DC mode. If the EL500x is operated faster than the time required for SSI communication and processing, this is indicated through the SyncError status bit.

The DC mode is set under the DC tab and becomes active after a TwinCAT restart or reload.

Commissioning instructions 5:

Optimized jitter from firmware 03 (EL5002-0000-0020)

The device-specific time jitter of the EL5002 has been optimized to a maximum value of ±100 ns. See chapter "Basic function principles and notes"

Commissioning instructions 6:
DC mode settings

Process data

For each channel the EL500x offers the position value (4 bytes) and status information (1 or 2 bytes). A differentiation should be made:

In the following example are three EL5001 devices are configured in order to illustrate the differences.

Commissioning instructions 7:
EL500x process data
Commissioning instructions 8:

SubVariables and TwinCAT 2.10

Under TwinCAT 2.10 the consolidated representation of subvariables as shown for 16-bit status in Fig. EL500x process data is not possible. Only the individually linkable bits are shown.

Commissioning instructions 9:
Representation of the SSI inputs in the TwinCAT tree

Start of SSI communication

If the start time of the SSI communication is of interest, it can be calculated in the control system (TwinCAT 2.11 or higher). The following functions must be activated in the terminal:

System Manager | EL500x | Advanced settings | Behavior | IncludeDcShiftTimes = TRUE

Commissioning instructions 10:
EL500x shift times

Through this setting the System Manager specifies for each terminal the fixed offset/shift between the local sync signal and the master-side DC sync in [µs]. This value is constant at runtime. Depending on the DC mode (InputBased or not) the local time of the SSI start may be cyclically calculated as follows, for example:

StartSSI = DCPLC + DcInputShift

This calculation must be performed in each PLC cycle. Further information can be found under Basic EtherCAT documentation.