CAN Resistor Emulator Card

Resistor ID

Resistor IDs are ordinal numbers of resistance channels.

Byte 1 can take odd values from 1 to 7.

Byte 4 can take even values from 2 to 8.

Resistance Values

Byte 2 is the Most significant Byte of the resistance 16-bit value of the resistor with ID1.

Byte 3 is the Least significant Byte of the resistance 16-bit value of the resistor with ID1.

Byte 2 is the Most significant Byte of the resistance 16-bit value of the resistor with ID2.

Byte 2 is the Least significant Byte of the resistance 16-bit value of the resistor with ID2.

The method for calculating the 16-bit value is the following:

$R_{binary}=\frac{R_{actual}}{R_{LSB}}$

$R_{binary}$ is a binary representation of the resistance value that should be send as a 16-bit message to the resistor emulator. This value takes a range from 0x0000 to 0xFFFF.

$R_{actual}$ is the actual value of the resistance which we want to emulate. Note that it will be rounded to an integer multiple of the $R_{LSB}$ value.

$R_{LSB}$ is the least significant bit in the binary weighted network of the resistors soldered to the emulation card. For this card, this is 10 Ω.

CAN Message example

Channels to be set: 3 and 4 with values 156559 Ω and 10000 Ω respectively

$R_{binary3}=\frac{R_{actual3}}{R_{LSB}} =\frac{156559}{10}=15655.9 \left[real\right]=15656 \left[integer\right]$

$R_{binary4}=\frac{R_{actual4}}{R_{LSB}} =\frac{10000}{10}=1000 \left[real\right]=1000 \left[integer\right]$

Table 5. Example CAN Message

Byte	1	2	3	4	5	6
Message	RES1	MSB1	LSB1	RES2	MSB2	LSB2
Data	0X03	0X03D	0X28	0X04	0X03	0XE8