Mitsubishi Electric MELSEC-F FX3U-CAN User Manual page 180

FX -CAN User's Manual
3U
Example 2:
Layer 2 message 2 parameter A/B = H00000180
Layer 2 message 2 parameter C/D = H00000006
BFM #107 to #113 stores received messages with CAN-IDs H180, H182, H184 and H186 because ID bits 1
and 2 are not evaluated. Relation between received CAN message, BFM #20 bit 0 and "RTR/new/DLC" high
byte is shown below.
Note
Please remember that in this case all four messages are stored in the same location! If more than one of the
messages with ID H180, H182, H184 or H186 is received between two write operations BFM #20 = K1, only
the last received CAN-ID, DLC, and data is available in BFM #107 to #113.
CAN bus
BFM #20
bit 0
RTR/new/DLC
high byte
Behaviour until
Same as in the first example, the high byte value H07 after
once, since
But this time, it is required to check the 11 bit CAN-ID in the corresponding Layer 2 message (BFM #100 to
#399) to determine which message ID was received. In this case the last message is H0180, and the data of
this message is stored to the data BFM. The data of messages H0182 and H0186 are lost.
Note
In this example, it is expected that the PLC program resets the "RTR/new/DLC" flags after reading the data at
, , and
174
Message
H0184
H00 (no new data
Hxx H00
between
is similar to that described in example 1.
and the data bytes in the BFM are also the data received with the last message.
.
Message Message
H0182 H0186
H03 (new frame + data
and ) between
shows that the buffer was overwritten at least
9 CAN Layer 2 Mode
9.3 Pre-defined Layer 2 Message Configuration
Message
H0180
H07 (new frame + data
and overflow between
and )
and )