CAN Communication

You can find the command set at Command Set.

Addresses

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

The addresses used by the USBoard-USS4 are calculated from the base address by adding the following offsets.

Offset to base address Message
+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 Second answer to CMD_GET_DATA_9TO16
+6 Answer to CMD_READ_PARASET
+7 Answer to CMD_GET_ANALOGIN
+8 Answer to CMD_WRITE_PARASET
+9 Answer to CMD_WRITE_PARASET_TO_EEPROM

Commands

In the following, the CAN IDs are given as an offset to the base address, so +3 means base address plus 3.

CMD_CONNECT

Use this command to establish and check the connection to the board.

Command

ID: +0

CMD_CONNECT 0 0 0 0 0 0 0
Answer

ID: +1

CMD_CONNECT 1 2 3 4 5 6 7

CMD_SET_CHANNEL_ACTIVE

This command can be used to activate or deactivate individual sensors without transmitting the complete parameter set. Two bytes for the channels 1 to 8 and 9 to 16 contain the information whether the sensors should be active. These bytes are bit-coded, each bit representing the state of one sensor. Every active channel is marked with a 1.

For example, 0x1F as the first byte means channels 1 to 5 are active and channels 6 to 8 are not active.

Command

ID: +0

CMD_SET_CHANNEL_ACTIVE (Sensors 1 to 8) (Sensors 9 to 16) 0 0 0 0 0
Answer
No answer.

CMD_GET_DATA_1TO8

This command is used to request the readings of sensors 1 to 8.

Command

ID: +0

CMD_GET_DATA_1TO8 0 0 0 0 0 0 0
Answer (two parts)

IDs: +2, +3

CMD_GET_DATA_1TO8 0 Values for sensors 1-4 (one byte each) 0 (reserved)
CMD_GET_DATA_1TO8 1 Values for sensors 5-8 (one byte each) 0 (reserved)

The measurement values are given in cm.

CMD_GET_DATA_9TO16

This command is used to request the readings of sensors 9 to 16.

Command

ID: +0

CMD_GET_DATA_9TO16 0 0 0 0 0 0 0
Answer (two parts)

IDs: +4, +5

CMD_GET_DATA_9TO16 0 Values for sensors 9-12 (one byte each) 0 (reserved)
CMD_GET_DATA_9TO16 1 Values for sensors 13-16 (one byte each) 0 (reserved)

The measurement values are given in cm.

CMD_WRITE_PARASET

Use this command to transfer a complete parameter set to the USBoard-USS4. The parameters are stored volatile, which means that they will be lost when the board is switched off. To comfortably configure the board, use the graphical parameter editor.

After transmitting the parameter set, it will immediately be used by the board.

Command

ID: +0

The command consists of nine messages sent one after the other, each containing some bytes of the parameter set.

CMD_WRITE_PARASET 0 Bytes 1 to 6
CMD_WRITE_PARASET 1 Bytes 7 to 12
CMD_WRITE_PARASET 2 Bytes 13 to 18
CMD_WRITE_PARASET 3 Bytes 19 to 24
CMD_WRITE_PARASET 4 Bytes 25 to 30
CMD_WRITE_PARASET 5 Bytes 31 to 36
CMD_WRITE_PARASET 6 Bytes 37 to 42
CMD_WRITE_PARASET 7 Bytes 43 to 48
CMD_WRITE_PARASET 8 Bytes 49 to 54
Answer

ID: +8

Each message is answered individually. The first 8 answers are identical

CMD_WRITE_PARASET 0 0 0 0 0 0 0

and the last answer contains the sum of all bytes in the parameter set.

CMD_WRITE_PARASET low byte high byte 0 0 0 0 0

CMD_WRITE_PARASET_TO_EEPROM

Use this command to write a complete parameter set into the board’s EEPROM. The parameters are stored non-volatile, which means that they will be used again, the next time the USBoard-USS4 is switched on. To conveniently configure the board, use the graphical parameter editor.

The parameter set will immediately be used after transmission.

Command

ID: +0

The command works identically to CMD_WRITE_PARASET, the only difference is the use of the command byte CMD_WRITE_PARASET_TO_EEPROM.

Answer

ID: +9

The answer is identical to the answers to CMD_WRITE_PARASET, the only difference is the use of the command byte CMD_WRITE_PARASET_TO_EEPROM.

CMD_READ_PARASET

Use this command to read a complete parameter set from the USBoard-USS4.

Command

ID: +0

CMD_READ_PARASET 0 0 0 0 0 0 0
Answer

ID: +6

The answer consists of nine messages sent one after the other, each containing some bytes of the parameter set.

CMD_READ_PARASET 0 Bytes 1 to 6
CMD_READ_PARASET 1 Bytes 7 to 12
CMD_READ_PARASET 2 Bytes 13 to 18
CMD_READ_PARASET 3 Bytes 19 to 24
CMD_READ_PARASET 4 Bytes 25 to 30
CMD_READ_PARASET 5 Bytes 31 to 36
CMD_READ_PARASET 6 Bytes 37 to 42
CMD_READ_PARASET 7 Bytes 43 to 48
CMD_READ_PARASET 8 Bytes 49 to 54

CMD_GET_ANALOGIN

Use this command to acquire the data of the four analog inputs.

Command

ID: +0

CMD_GET_ANALOGIN 0 0 0 0 0 0 0
Answer

ID: +7

Because the resolution of the on-board AD-converter is 12 bit, the first part of the answer is made up of the four low bytes. Bytes 5 and 6 contain the upper 4 bits of the four channels.

CMD_GET_ANALOGIN low byte channel 1 low byte channel 2 low byte channel 3 low byte channel 4 high bits of channel 2 and 1 high bits of channel 4 and 3 0