Sendng CAN BCM Cyclic Message Has No Frame Contents - c++

Question

I need to transmit 1200 identical CAN messages, with 5ms between each message. This is to arm a motor to start. Because of the timing required, I switched from
sockfd = socket(PF_CAN, SOCK_RAW, CAN_RAW);
to
sockfd = socket(PF_CAN, SOCK_DGRAM, CAN_BCM);
Using a CAN sniffer, the 1200 messages are being sent at 5ms intervals. The data field has the correct data that I specified, but the 32-bit CAN_ID field is 0x00000000 instead of 0x00000201.
The code I wrote to send a TX_SETUP is shown below.
// these are placed here for testing
unsigned char priority = 0;
unsigned char srcaddr = 0;
unsigned char destaddr = 2;
unsigned objaddr = ESC::enumPWM;
struct {
struct bcm_msg_head msg_head;
struct can_frame frame[4];
} txmsg;
txmsg.msg_head.opcode = TX_SETUP;
txmsg.msg_head.nframes = 1;
// set flags first, set EFF for extended frame, no
// RTR, no ERR.
txmsg.frame[0].can_id = CAN_EFF_FLAG;
txmsg.frame[0].can_id |= ((0x1F & priority) << 24);
txmsg.frame[0].can_id |= (srcaddr << 16);
txmsg.frame[0].can_id |= (destaddr << 8);
txmsg.frame[0].can_id |= objaddr;
txmsg.msg_head.flags = SETTIMER | STARTTIMER | TX_CP_CAN_ID;
txmsg.msg_head.count = 1200;
txmsg.msg_head.ival1.tv_sec = 0;
txmsg.msg_head.ival1.tv_usec = 5000;
txmsg.msg_head.ival2.tv_sec = 0;
txmsg.msg_head.ival2.tv_usec = 0;
// configure the data to send
txmsg.frame[0].can_dlc = 2;
txmsg.frame[0].data[0] = 0x04;
txmsg.frame[0].data[1] = 0x4C;
txmsg.frame[0].data[2] = 0;
txmsg.frame[0].data[3] = 0;
txmsg.frame[0].data[4] = 0;
txmsg.frame[0].data[5] = 0;
txmsg.frame[0].data[6] = 0;
txmsg.frame[0].data[7] = 0;
int err = write(can->sockfd, &txmsg, sizeof(txmsg));
Any idea why the message is transmitting incorrectly?