Each resistive sensor channel consists of a set of twenty resistors, the combination of which defines the resistance value of the channel, in the range 0.5Ω and 262.14375kΩ.

The operator controls the resistance value from the RSM Run-Time Panel. This value is then transferred to the FPGA module of the card via the real-time model. From this value, the FPGA program determines the pattern of resistors to be activated to produce the desired resistance and applies this pattern value to the card via a 20-bit deserializer.

Each channel provides an input pin and a user-supplied reference input pin at the ELCO-56 connector. When the ECU signal is connected to the input pin, it is tied to either the user-supplied reference voltage (USRx) or GND, through the programmed resistor set,

The 20 individual resistance values are listed below. the current sensing circuitry adds a 0.47Ω resistance.

Resistance Position	Resistance Value
19	131072
18	65536
17	32768
16	16384
15	8192
14	4096
13	2048
12	1024
11	512
10	256
9	128
8	64
7	32
6	16
5	8
4	4
3	2
2	1
1	0.5
0	0.25

Termination voltage

For each channel, the user is able to select the termination voltage via a drop-down list in the RSM Configuration Panel. The three choices are Open, Ground, and User-Defined Voltage.

The inputs default state is Open circuit state and this is achieved by opening both of the termination voltages.
When User-Defined voltage is selected, the user must supply a reference voltage on the corresponding USRx input.

Both the Input and the User Supplied Termination voltage are Operating Voltage tolerant.

Current direction protection

A voltage comparator signals the current flow (I_DIR0) and the 4 input switch allows to select the current flow direction (DIR_?0) when operating between the Input and the User supply reference voltage.

Power dissipation and over current protection

Each input is able to support 1/4 watt of dissipation. The table below illustrates the power range detection for all the resistor range.

As shown in the sensor diagram above, a sampling (SH0) and buffer (CAPON0) mechanism allows limiting the transition between resistor values within 5% overshoot/undershoot. A current sense circuit monitors the current within the circuit and opens it when the power dissipation exceeds ¼ watt. As power dissipation is function of the selected resistance, an Analog To Digital Converter (ADCK0, nADCS0, ISENSE0) is used to monitor the flowing current. The control module monitors continuously the current. Upon detecting a fault, it reports an error and opens the circuit.

When an error condition is detected, the fault is reported via the model to the user interface. After removing the fault condition, the operator can acknowledge the fault from the RSM Run-Time Panel. The fault is then cleared by the FPGA module if the condition is no longer present, otherwise, the fault is raised again.

Maximum voltage values for different patterns of resistances

RANGE	Res Reg	R	R real	Vmax	Imax	Vr	Vadc

0x1F	0	5.00	5.00	1.12	0.22	1.12	1387.72
0x13	1	0.24	5.24	1.14	0.22	1.09	1355.57
0x12	2	0.47	5.47	1.17	0.21	1.07	1326.76
0x12	3	0.71	5.71	1.19	0.21	1.05	1298.58
0x11	4	1.00	6.00	1.22	0.20	1.02	1266.81
0x11	7	1.71	6.71	1.30	0.19	0.97	1197.91
0x10	8	2.00	7.00	1.32	0.19	0.94	1172.84
0x10	F	3.71	8.71	1.48	0.17	0.85	1051.42
0xF	10	4.00	9.00	1.50	0.17	0.83	1034.34
0xF	1F	7.71	12.71	1.78	0.14	0.70	870.39
0xE	20	8.00	13.00	1.80	0.14	0.69	860.63
0xE	3F	15.71	20.71	2.28	0.11	0.55	681.86
0xD	40	16.00	21.00	2.29	0.11	0.55	677.14
0xD	7F	31.71	36.71	3.03	0.08	0.41	512.15
0xC	80	32.00	37.00	3.04	0.08	0.41	510.14
0xC	FF	63.71	68.71	4.14	0.06	0.30	374.35
0xB	100	64.00	69.00	4.15	0.06	0.30	373.56
0xB	1FF	127.71	132.71	5.76	0.04	0.22	269.36
0xA	200	128.00	133.00	5.77	0.04	0.22	269.07
0xA	3FF	255.71	260.71	8.07	0.03	0.15	192.18
0x9	400	256.00	261.00	8.08	0.03	0.15	192.07
0x9	7FF	511.71	516.71	11.37	0.02	0.11	136.51
0x8	800	512.00	517.00	11.37	0.02	0.11	136.47
0x8	FFF	1023.71	1028.71	16.04	0.02	0.08	96.75
0x7	1000	1024.00	1029.00	16.04	0.02	0.08	96.73
0x7	1FFF	2047.71	2052.71	22.65	0.01	0.06	68.49
0x6	2000	2048.00	2053.00	22.66	0.01	0.06	68.48
0x6	3FFF	4095.71	4100.71	32.02	0.01	0.04	48.46
0x5	4000	4096.00	4101.00	32.02	0.01	0.04	48.46
0x5	7FFF	8191.71	8196.71	45.27	0.01	0.03	34.27
0x4	8000	8192.00	8197.00	45.27	0.01	0.03	34.27
0x4	7FFF	16383.71	16388.71	64.01	0.00	0.02	24.24
0x3	10000	16384.00	16389.00	64.01	0.00	0.02	24.24
0x3	1FFFF	32767.71	32772.71	90.52	0.00	0.01	17.14
0x2	20000	32768.00	32773.00	90.52	0.00	0.01	17.14
0x2	3FFFF	65535.71	65540.71	128.00	0.00	0.01	12.12
0x1	40000	65536.00	65541.00	128.00	0.00	0.01	12.12
0x1	7FFFF	131071.71	131076.71	181.02	0.00	0.01	8.57
0x0	80000	131072.00	131077.00	181.02	0.00	0.01	8.57

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