CXAIN Command - Analog Input Configuration

Configures the interpretation of magnitudes read by the device’s AD inputs, allowing transformation and scaling of values according to the application.

What is it for?

Use case	Description
📊 Fuel sensors	Convert voltage to liters or percentage
🌡️ Temperature sensors	Transform analog signal to °C
⚡ Voltage measurement	Scale voltage readings
📈 Custom calibration	Adjust readings to specific units

It is recommended to recalibrate the analog reading constant through the AR Command
The AD value reading for each input can be obtained through the AIN Command
To query all readings obtained from all AD inputs of the device or generate a report with these values, use the AD Report

Commands

Configure


SCXAINaabccccdeeeefgggghiiiijkkkklmmmm

Query


QCXAINaa

Response


RCXAINaabccccdeeeefgggghiiiijkkkklmmmm

Parameters

Field	Description	Range
aa	Analog input index	`00`, `01`, `02`, `07`
b	Sign of lower output limit (BOTTOM)	`+` / `-`
cccc	Magnitude of lower output limit (BOTTOM)	`0000`–`9999`
d	Sign of upper output limit (TOP)	`+` / `-`
eeee	Magnitude of upper output limit (TOP)	`0000`–`9999`
f	Sign of first calibration point voltage (XA)	`+` / `-`
gggg	First calibration voltage XA in hundredths of a volt (`0500` = 5.00 V)	`0000`–`9999`
h	Sign of second calibration point voltage (XB)	`+` / `-`
iiii	Second calibration voltage XB in hundredths of a volt (`0500` = 5.00 V)	`0000`–`9999`
j	Sign of output value at the first point (YA)	`+` / `-`
kkkk	Output value corresponding to XA (YA) — free unit	`0000`–`9999`
l	Sign of output value at the second point (YB)	`+` / `-`
mmmm	Output value corresponding to XB (YB) — free unit	`0000`–`9999`

How the reported value is computed

The device performs a linear interpolation between the two points (XA, YA) and (XB, YB) over the measured voltage, then clamps the output to the [BOTTOM, TOP] range:


Y = YA + (Vin − XA) · (YB − YA) / (XB − XA)
output = clamp(Y, BOTTOM, TOP)

Vin is expressed in hundredths of a volt (same as XA and XB).
YA, YB, BOTTOM and TOP are in the output unit of your choice (liters, %, °C, mV, etc.).
The clamp ensures that voltages outside the calibrated range never produce nonsense values.

XA and XB are hundredths of a volt, not tenths. For example:

0500 = 5.00 V
1230 = 12.30 V
3300 = 33.00 V

Mixing up the scale (writing 0050 thinking “5 V”) is the most common mistake when configuring this command.

Examples

Resistive fuel sensor 0–5 V → 0–100 %

Linear sensor whose output ranges from 0 V (empty tank) to 5 V (full tank).


>SCXAIN01+0000+0100+0000+0500+0000+0100<
// aa   = 01     → input AD1
// BOT  = +0000  → lower output clamp = 0 %
// TOP  = +0100  → upper output clamp = 100 %
// XA   = +0000  → 0.00 V  (empty tank)
// XB   = +0500  → 5.00 V  (full tank)
// YA   = +0000  → 0 %
// YB   = +0100  → 100 %

Capacitive fuel sensor 0–33 V → 0–200 L

Higher-range sensor (common on trucks) that delivers up to 33 V for a 200-liter tank.


>SCXAIN01+0000+0200+0000+3300+0000+0200<
// XA = 0.00 V   → 0 L
// XB = 33.00 V  → 200 L
// Output clamped to [0, 200] liters

Temperature sensor 0–5 V → −40 °C to +150 °C

Output with negative offset: at 0 V the sensor reports −40 °C; at 5 V it reports +150 °C.


>SCXAIN01-0040+0150+0000+0500-0040+0150<
// BOT  = -0040  → minimum reported = −40 °C
// TOP  = +0150  → maximum reported = +150 °C
// XA   = +0000  → 0.00 V → YA = -0040 (−40 °C)
// XB   = +0500  → 5.00 V → YB = +0150 (+150 °C)

Direct battery reading 0–36 V

Identity mapping in hundredths of a volt: the output equals the voltage (1245 → 12.45 V).


>SCXAIN01+0000+3600+0000+3600+0000+3600<
// XA = 0.00 V   → YA = 0
// XB = 36.00 V  → YB = 3600
// Output clamped to [0, 3600] (hundredths of a volt)

Passthrough — no transformation (raw ADC value)

Useful when you want to obtain the raw ADC reading with no scaling. This is the factory default.


>SCXAIN01-9999+9999-0000+0001-0000+0001<
// Unit slope with clamp at [-9999, +9999]
// Equivalent to applying no conversion

To query the current configuration of any input, use QCXAINaa. The device responds with an RCXAIN that has the exact same format as the SCXAIN previously sent:


>QCXAIN01<
>RCXAIN01+0000+0100+0000+0500+0000+0100<

Compatibility

💾Firmware:v1.00.00

SPLegacy

ULLegacy

MTLegacy

C3Legacy

C5Legacy

SP-IOT

SM-IOT

ZE-IOT