Process data communication – Baumer G0-GB-GXP5W/S/H-GXU5W/S User Manual

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Baumer IVO GmbH & Co. KG

20.11.12

Villingen-Schwenningen, Germany

SDO examples

Request
of a value by the master from the slave
A frequent request will be a request for position.  Object 6004h

COB ID

DLC Command

Object L

Object H Subindex Data 0

Data
1

Data
2

Data
3

600h+node ID

8

40h

04h

60h

0

x

x

x

x


Response by the slave to the request for a value
The position is 4 bytes long, the precise values can be found under object 6004h.

COB ID

DLC Command

Object L

Object H Subindex Data 0

Data
1

Data
2

Data
3

580h+node ID

8

43h

04h

60h

0

a

b

c

d


Writing of a value by the master into the slave
Position setting can be performed with preset.  Object 6003h

COB ID

DLC Command

Object L

Object H Subindex Data 0

Data
1

Data
2

Data
3

600h+node ID

8

22h

03h

60h

0

a

b

c

d


Slave's response to the writing of a value

COB ID

DLC Command

Object L

Object H

Subindex Data 0 Data

1

Data
2

Data
3

580h+node ID

8

60h

03h

60h

0

0

0

0

0



3.3.4. Process data communication

Process data objects are used for real time data exchange for process data, for example position or operating
status. PDOs can be transmitted synchronously or cyclically (asynchronously). The encoder supports the
PDO1 and the PDO2. Both PDOs supply the current position of the encoder and are defined in the objects
1800h, 1801h, 1A00h, 1A01, 2800h, 2801h and 6200h.

Synchronous
In order to transmit the process data synchronously, a value between 1 and F0h (=240) must be written into
the object 1800h / 1801h Subindex 2. If the value is 3, the PDO is transmitted on every third sync telegram (if
the value 1 is entered, transmission takes place on every sync telegram), as long as there is a 0 written into
the object 2800h / 2801h. If it contains for example a 5, the PDO will continue to be written as before on every
third Sync telegram, but only a total of 5 times. Accordingly, the last PDO is written on the 15th sync
telegram. The counter for the number of PDOs to be transmitted is reset in the event of a position change or
NMT reset, i.e. unless it is changed, the position is transmitted five times. If the position changes, it is
transmitted a further five times.
In synchronous operation, the PDO is requested by the master via the Sync telegram.

Byte 0

Byte 1

COB ID = 80

0


Cyclical (asynchronous)
If you wish the PDOs to be transmitted cyclically, the value FEh must be written into the object 1800h / 1801h
Subindex 2. In addition, the cycle time in milliseconds must be entered in the same object subindex 5. The
entered time is rounded off to 1 ms. If the value is stored for 0 ms, the PDOs are not transmitted. The function
is switched off.
The object 2800h / 2801h offers another possibility: If the value is 0, cyclical transmission runs as described
above. If the value is 1, a cyclical test is performed as to whether a change of the value has occurred. If not,
no transmission takes place. If the value is 4, the PDO is transmitted four times with each cycle if there is a
change.

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