Command Set

Command IDs

The following table shows the available commands of the USBoard-USS5.

Command Value Description
CMD_CONNECT 0 Check connection
CMD_SET_CHANNEL_ACTIVE 1 Activate channel for sending / receiving
CMD_GET_DATA_1TO8 2 Request data of sensors 1 to 8
CMD_GET_DATA_9TO16 3 Request data of sensors 9 to 16
CMD_WRITE_PARASET 4 Upload parameter set to board (volatile)
CMD_WRITE_PARASET_TO_EEPROM 5 Write parameter set to board’s EEPROM (non-volatile)
CMD_READ_PARASET 6 Read current parameter set
CMD_GET_ANALOGIN 7 Read values of analogue inputs
8-12 Reserved
CMD_GET_DATA 13 Request data of all sensors

CAN Communication

The default base address is 0x400. This base address can be changed in the parameter set.

The addresses used by the USBoard-USS5 are calculated from the base address by adding the following offsets.

Offset to base address Function
+0 Receive commands
+1 Answer to CMD_CONNECT
+2 First answer to CMD_GET_DATA_1TO8
+3 Second answer to CMD_GET_DATA_1TO8
+4 First answer to CMD_GET_DATA_9TO16
+5 2nd answer to CMD_GET_DATA_9TO16
+13 1st Answer to CMD_GET_DATA (group 0: 1 to 4)
+14 2nd Answer to CMD_GET_DATA (group 1: 5 to 8)
+15 3rd Answer to CMD_GET_DATA (group 2: 9 to 12)
+16 4th Answer to CMD_GET_DATA (group 3: 13 to 16)

USB / Serial Interface

Communication via USB is done via a USB-serial-converter on the USBoard-USS5. The computer’s operating system can access it like a traditional serial interface. On request the USB converter can be replaced by an RS-232 transmitter. This does not affect the communication protocol of the serial interface.


The RS-232 interface requires a common ground connection between the USBoard-USS5 and the computer.

The serial interface runs at 19200 Baud. Its protocol has the same format as the CAN communication except for the following addition:

Every message from the USBoard-USS5 begins with a start byte which must have the value 0xFF. After each message, made up of eight data bytes, a 16 bit checksum is sent. Because of this, a complete message is 11 bytes long.

Byte 1 Bytes 2-9 Byte 10 Byte 11
0xFF data bytes checksum high byte checksum low byte

The checksum is calculated with an CRC-CCITT algorithm using 8 databytes.

Messages to the USBoard-USS5 only contain the data bytes.

Example implementation of the checksum calulation (C code):

unsigned int getCheckSum(unsigned char *c, size_t iNumBytes){
	unsigned int uCrc16;
	unsigned char ucData[2];
	size_t i;

	uCrc16 = 0;
	ucData[0] = 0;
	for(i=0; i<iNumBytes; i++){
		ucData[1] = ucData[0];
		ucData[0] = c[i];

		if(uCrc16 & 0x8000){
			uCrc16 = (uCrc16 & 0x7fff) << 1;
			uCrc16^= 0x1021;
			uCrc16 <<= 1;
		uCrc16^= (unsigned int)(ucData[0]) | ((unsigned int)(ucData[1]) << 8);

	return uCrc16;