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Functions
5.1 CANopen
Cyclic data exchange: Calculation of net and gross data
PROFINET limits
Gross data length for input/output data of an IO device: 1440 bytes
Gross data length for input and output data of an IO device: 2880 bytes
Net data length for input/output data of an IO device: 1280 bytes
Gross data length for input and output data of an IO device: 2560 bytes
The calculation of the gross and net data of an IO device is performed during the compile. If
the limit values are exceeded, an error message is displayed at the interface.
Net data
The net data of the PN/CAN LINK is the data for which I/O addresses are assigned, i.e. for
modules (CANopen Manager, CANopen Slave, CAN transparent) and CAN process data.
Gross data
In cyclic data exchange, additional status bytes are transmitted to ensure consistency. The
sum of net data and status bytes provides the gross data.
• Each submodule with IO data has one status byte for input data and one status byte for
output data. These submodules are PN/CAN LINK (rack 0, slot 0), interface and ports.
• In addition to the configured data bytes (net data), each submodule with only input or
output data has a status byte for input data and a status byte for output data. These
submodules are the CAN process data (OD data, messages).
• Each submodule with input and output data has two status bytes for input data and two
status bytes for output data in addition to the configured data bytes (net data). These
submodules are the CAN process data (proxies).
Submodule
PN/CAN LINK (rack 0,
slot 0)
Interface
Port 1
Port 2
CANopen network
Transmit data/transmit
message
Receive data/receive
message
Transmit and receive
data
Example with PN/CAN LINK
40
Input data (bytes)
Output data (bytes)
0
0
0
0
0
0
0
0
1
1
0
x
y
0
y
x
Status byte input
Status byte output
data
data
1
1
1
1
1
1
1
1
2
2
1
1
1
1
2
2
Operating Instructions, 03/2022, A5E39895388-AC
SIMATIC PN/CAN LINK
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