Process data

This section describes the individual PDOs and their content. A PDO (Process Data Object) is a unit on cyclically transmitted process values. Such a unit can be an individual variable (e.g. the weight as a 32-bit value) or a group/structure of variables. The individual PDOs can be activated or deactivated separately in the TwinCAT System Manager. The "Process data" tab is used for this (visible only if the box is selected on the left). A change in the composition of the process data in the TwinCAT System Manager becomes effective only after restarting the EtherCAT system.

The EPP3356-0022 can be used in 2 basic operating modes

The basic operating mode of the EPP3356-0022 is determined by the selection of the process data (PDO). The procedure for the selection of the process data can be found in chapter Selection of the process data.

Predefined PDO Assignment

In order to simplify the configuration, typical configuration combinations of process data are stored in the device description. The predefined configurations can be selected in the process data overview. Therefore the function is available only if the ESI/XML files are saved in the system.

The following combinations are possible:

Process data 1:

Default process image

The default process image is standard (INT32).

Process data 2:

Function of the variables

Variable: Status

Meaning: The status word (SW) is located in the input process image, and is transmitted from box to the controller.

Bit

SW. 15

SW. 14

SW. 13

SW.12

SW. 11

SW. 10

SW. 9

SW. 8

SW. 7

SW. 6

SW. 5

SW. 4

SW. 3

SW. 2

SW. 1

SW. 0

Name

TxPDO Toggle

-

Sync Error

-

-

-

-

Steady State

Calibration in progress

Error

-

-

Data invalid

-

Overrange

-

Meaning

Toggles 0→1->0 with each updated data set

-

Synchronisation error

 

Idling recognition

Calibration in progress

Collective error display

-

-

Input data are invalid

-

Measuring range exceeded

-

Variable: Value

Meaning: Calculated 32-bit DINT load value in unit [1], with sign

Variable: Value (Real)

Meaning: Calculated 32-bit fixed point REAL load value with mantissa and exponent in unit [1]

The format matches the REAL format of IEC 61131-3, which in turn is based on the REAL format of IEC 559. A REAL number (single precision) is defined as follows (See also Beckhoff InfoSys: TwinCAT PLC Control: standard data types). In accordance with IEC 61131 this 32-bit variable can be directly linked with a FLOAT variable of the PLC.

Bitposition (from the left)

1

8

23 (+1 „hidden bit“, see IE559)

Function

Sign

Exponent

Mantissa

Variable: WcState

Meaning: Cyclic diagnostic variable; „0“ indicates correct data transmission

Variable: Status

Meaning: State of the EtherCAT device; State.3 = TRUE indicates correct operation in OP

Variable: AdsAddr

Meaning: AmsNet address of the EtherCAT device from AmsNetId (in this case: 192.168.0.20.5.1) and port (in this case: 1003)

Variable: Ctrl

Meaning: The control word (CW) is located in the output process image, and is transmitted from the controller to the box.

Bit

CW. 15

CW. 14

CW. 13

CW. 12

CW. 11

CW. 10

CW. 9

CW. 8

CW. 7

CW. 6

CW. 5

CW. 4

CW. 3

CW. 2

CW. 1

CW. 0

Name

-

Tara

Sample Mode

Input Freeze

Disable Calibration

Start Calibration

Meaning

-

starts tare

mode switching (EL3356-0010 and EP3356-0022only)

stops the measurement

Switches the automatic self-calibration off

Starts the self-calibration immediately

See also the example program for the dissection of the Status and CTRL variable.

Variants (Predefined PDO)

Fixed-point representation of the load

The display of the load value can also be converted already in the box into a point representation. To do this the input PDOs are to be changed as follows:

Process data 3:

Variable: Value (Real)

Meaning: Calculated 32-bit fixed point REAL load value with mantissa and exponent in unit [1]

The format matches the REAL format of IEC 61131-3, which in turn is based on the REAL format of IEC 559. A REAL number (single precision) is defined as follows (See also Beckhoff InfoSys: TwinCAT PLC Control: standard data types). This 32-bit variable can be linked directly with a FLOAT variable of the PLC according to IEC61131.

Bit position (from left)

1

8

23 (+1 „hidden bit“, see IEC 559)

Function

Sign

Exponent

Mantissa

Voltage measurement

The EPP3356-0022 can also be used as a 2-channel analog input box for voltage measurement, see Notes.

Process data 4:

Variable

Meaning

Underrange

Measurement is below range

Overrange

Measuring range exceeded

Error

Collective error display

TxPDO Toggle

Toggles 0→1→0 with each updated data set

Value

Right-justified voltage value over the respective measuring range (Range of values 0x80.00.00.00…0…0x7F.FF.FF.FF)

Channel 1: supply voltage

Channel 2: bridge voltage

Distributed Clocks

In DC mode (Distributed Clocks) the process data x1A03 Timestamp must be activated.

Process data 5:

Also, the variables DcOutputShift and DcInputShift are displayed in the process data in DC mode. Upon activation of the configuration these are calculated once in the unit [ns] on the basis of the set EtherCAT cycle time (observe assigned task!) and DC shift times from the EtherCAT master settings. In the InputBased operating mode, DcInputShift indicates by how many nanoseconds [ns] before or after the global Sync the box determines your process data. For further information on this, see the EtherCAT system description.

Since the EPP3356-0022 is not DC-triggered but determines the timestamp itself, these values have no meaning in the EPP3356-0022.

Sync Manager (SM)

PDO Assignment

Inputs: SM3, PDO Assignment 0x1C13

Index

Index of excluded PDOs

Size (byte.bit)

Name

PDO content
Index - Name

0x1A00 (default)

-

2.0

RMB Status (Resistor Measurement Bridge)

0x6000:02 - Overrange
0x6000:04 - Data invalid
0x6000:07 - Error
0x6000:08 - Calibration in progress
0x6000:09 - Steady State
0x1C32:20 - Sync Error
0x1800:09 - TxPDO Toggle

0x1A01 (default)

0x1A02
0x1A04
0x1A05
0x1A06
0x1A07

4.0

RMB Value (INT 32)

0x6000:11 - Value

0x1A02

0x1A01
0x1A04
0x1A05
0x1A06
0x1A07

4.0

RMB Value (Real)

0x6000:12 - Value

0x1A03

0x1A04
0x1A05
0x1A06
0x1A07

8.0

RMB Timestamp

0x6000:13 - Value

0x1A04

0x1A00
0x1A01
0x1A02
0x1A03
0x1A05

6.0

AI Standard Channel 1 (Analog Input)

0x6010:01 - Underrange
0x6010:02 - Overrange
0x6010:07 - Error
0x6010:10 - TxPDO Toggle
0x6010:11 - Value

0x1A05

0x1A00
0x1A01
0x1A02
0x1A03
0x1A04

4.0

AI Standard Channel 1 (Analog Input)

0x6010:11 - Value

0x1A06

0x1A00
0x1A01
0x1A02
0x1A03
0x1A07

6.0

AI Standard Channel 2 (Analog Input)

0x6020:01 - Underrange
0x6020:02 - Overrange
0x6020:07 - Error
0x6020:10 - TxPDO Toggle
0x6020:11 - Value

0x1A07

0x1A00
0x1A01
0x1A02
0x1A03
0x1A06

4.0

AI Standard Channel 2 (Analog Input)

0x6020:11 - Value

Outputs: SM2, PDO-Zuordnung 0x1C12

Index

Index ausgeschlossener PDOs

Größe (Byte.Bit)

Name

PDO Inhalt

0x1600 (default)

-

2.0

RMB Control (Resistor Measurement bridge)

0x7000:01 - Start calibration
0x7000:02 - Disable calibration
0x7000:03 - Input freeze
0x7000:04 - Sample Mode
0x7000:05 - Tara