Hi,
MB ID is set using FlexCAN_Ip_ConfigRxMb function. In your example using std. ID and individual masking scheme set std.ID=0x126 using
FlexCAN_Ip_ConfigRxMb(INST_FLEXCAN_0, RX_MB_IDX_0, &rx_info, 0x126); // set MB std ID = 0x126
If all mask bits are set a message with exact matched ID is received, so only std.ID 0x126 FlexCAN_Ip_SetRxIndividualMask_Privileged(INST_FLEXCAN_0,RX_MB_IDX_0,0x7FF<<18); // Mask = 0x7FF
If all mask bits are cleared all std.ID messages will be received into RX_MB_IDX_0 FlexCAN_Ip_SetRxIndividualMask_Privileged(INST_FLEXCAN_0,RX_MB_IDX_0,0x0<<18); // Mask = 0x0
You can also create ID range to be received
FlexCAN_Ip_SetRxIndividualMask_Privileged(INST_FLEXCAN_0,RX_MB_IDX_0,0x7FC<<18); // Mask = 0x7FC
Here messages with ID range 0x124-0x127 are received, lower 2 bits are don't care.
BR, Petr