Cyclic Data Exchange Between Controller And Pn/Can Link For Configured Can Messages - Siemens Simatic Operating Instructions Manual

Note
For values made up of multiple bits, the first bit is the MSB and the last bit is the LSB.
Example: Bit 1 ... 0 = 2 means: Bit 0 = "0" and bit 1 = "1".
4.2.5 Cyclic data exchange between controller and PN/CAN LINK for configured
CAN messages
CAN messages with PROFINET output data (transmit message modules)
"Transmit message modules" can be configured in the TIA Portal. Each of these modules
has its own message ID, which is configured in the TIA Portal, and its own data, which is
transmitted cyclically to the PN/CAN LINK via PROFINET in the output process image of the
S7 controller.
The PN/CAN LINK sends a CAN message with the message ID and the current data:
● When the data changes
● When a CAN RTR frame (Remote Transmit Request) has been received with the
matching message ID
● During transition of the PN/CAN LINK to "ON" state
● Cyclically, if configured accordingly
The triggers are independent of one another. That is, the configured transmit cycle is
retained even if a message based on a data change or an RTR has been sent in the interim.
If configured, the PN/CAN LINK changes the order of specific data bytes for fixed CAN
messages prior to sending to compensate for the different "endianness" of PROFINET and
CAN. PROFINET uses "Big Endian", CAN usually uses "Little Endian". In the case of
programmed CAN messages, however, the order of the data bytes is not changed.
SIMATIC PN/CAN LINK
Operating Instructions, 03/2018, A5E39895388-AB
Functions
4.2 CAN transparent
47