Siemens Simatic Operating Instructions Manual page 56

Functions
4.2 CAN transparent
Changing the receive filters during runtime
The receive filter can be changed from the S7 user program at runtime by writing a data
record to the data record index 0x210 of a receive proxy module.
The PN/CAN LINK makes the corresponding data record available on the respective receive
proxy module.
Each receive proxy module can have up to 16 receive filters. If a received CAN message
matches one of the filters, it is entered in the receive buffer.
Each individual filter consists of a 32-bit value "Criterion" and a 32-bit value "Mask".
If a bit in "Mask" is "0", the received CAN messages are not checked against the
corresponding bit in the "Criterion".
To ensure that a bit set in "Criterion" acts as a filter, the corresponding bit in the "Mask" must
be set to "1".
Structure of the data to be written with WRREC
Data record size: 8*n bytes; n = Number of filters = 1 to 16.
Criterion filter 1 (32-bit, Big Endian)
Mask filter 1 (32-bit, Big Endian)
Criterion filter 2 (32-bit, Big Endian)
Mask filter 2 (32-bit, Big Endian)
...
Criterion filter 16 (32-bit, Big Endian)
Mask filter 16 (32-bit, Big Endian)
Note
If the number of written bytes is not a multiple of "8", the extra bytes are ignored. A maximum
of 16 filters with 4 bytes each for Criterion and Mask are permitted. If the number of written
bytes is ≥ 128, the write access (WRREC) is rejected with PROFINET error code
0xDF80B100 and the filter remains unchanged.
54
SIMATIC PN/CAN LINK
Operating Instructions, 03/2018, A5E39895388-AB