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

Functions
4.2 CAN transparent
CAN messages with PROFINET input data (receive message modules)
"Receive 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 from the PN/CAN LINK to the S7 controller via PROFINET as part of
the input process image.
The values of the input data are assigned during configuration of the PN/CAN LINK by the
S7 controller according to the configuration.
If a CAN frame with the configured message ID has been received, the order of the data
bytes is first changed, if necessary, to correct the "endianness" before the data is transferred
to the input data for the S7 controller.
A setting can be made during configuration so that the PN/CAN LINK transmits an RTR
frame with the configured message ID during transition to the PN/CAN LINK state "ON" on
the CAN bus. This frame requests that the associated counterpart sends the corresponding
data message.
As soon as a PN/CAN LINK changes to "ON" state, it monitors the receipt of CAN messages
of all configured message IDs and transmits information about them, compressed into one
status bit, to the S7 controller. As long as there is at least one configured message ID from
which a CAN message has not yet been received, a zero is transmitted to the S7 controller
in the status bit.
4.2.6 Cyclic data exchange between controller and PN/CAN LINK for programmed
CAN messages
"Transmit proxy modules" and "receive proxy modules" can be set up in the TIA Portal.
These modules serve as a "communication channel" that enables the S7 user program to
send and receive any messages not configured beforehand.
The use of multiple transmit / receive proxy modules makes for easier programming of the
S7 user program because these modules represent communication channels that are
independent of one another.
Example of transmit proxy module: Two code locations want to transmit CAN messages.
When you set up two transmit proxies, these messages do not have to be synchronized or
matched. Each code location uses its own proxy.
Example of receive proxy module: Because each receive proxy module has its own "receive
filter list", you can use multiple proxy modules to pre-filter messages by CAN ID, for
example, one receive proxy for "commands" only and one receive proxy for "status
messages".
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SIMATIC PN/CAN LINK
Operating Instructions, 03/2018, A5E39895388-AB