Measuring Pressure and Temperature on One Sensor: How to Specify and Wire an I²C / SPI Dual-Output Sensor
For pressure and temperature at one measurement point, consider a dual-output sensor with I²C or SPI. The RS-PM160-DV digital interfaces provide both values; the voltage-only version does not provide temperature. Replacing a separate temperature probe also requires suitable temperature accuracy, thermal contact and response.
When dual output is actually worth it
Dual output is useful for recording pressure and temperature at one point, assessing equipment condition or integrating an MCU acquisition node. Cost and hardware savings depend on temperature accuracy, thermal response, interface development and mounting. A temperature rise alone does not identify a fault or medium.
The opposite case: if your system has only PLC analogue inputs and no MCU, digital output is poor value. An analogue transmitter with 4-20 mA or 0-10 V output is the simpler buy.
Choosing the interface: I²C, SPI, or digital plus voltage
Our RS-PM160DV digital pressure and temperature sensor offers three digital-capable output configurations, and the variant determines both your wiring and what data you can actually get:
| Output variant | What you can read | Best for |
|---|---|---|
| I²C digital | Pressure + temperature | Board-level integration, short runs, direct MCU connection; slave address 0x6D |
| SPI digital | Pressure + temperature | SPI host integration; confirm the required mode, timing and throughput |
| I²C + analogue voltage | Voltage gives pressure; temperature needs I²C | Feeding a PLC or DAQ card while keeping a digital port for the MCU |
Here is the mistake that gets ordered most often: the pure analogue voltage variant outputs no temperature signal. Temperature is only available over I²C or SPI. If temperature is a hard requirement, the digital port must stay in the order — do not simplify it down to voltage-only.
Second constraint, on the connector: the M12 connector version supports voltage output or I²C only — not the combined I²C + voltage mode, and not SPI. Dual-mode output requires the cable version.
Reading the key parameters
| Item | Value | Note |
|---|---|---|
| Accuracy @25 °C | ±0.10 % FS | Room-temperature calibration figure, not full-range behaviour |
| Total Error Band, range ≥1 bar | Typical ±0.25 % FS, maximum ±0.50 % FS; -20 to 85 °C | Table values by range; for ≤2 bar also confirm the datasheet footnote and order |
| Total Error Band, range <1 bar | Typical ±0.50 % FS, maximum ±1.00 % FS; -10 to 70 °C | Low-pressure ranges have a narrower compensated band |
| Supply voltage | 3.0 to 5.5 V DC | 3.3 V version at 3.3±5 % VDC; 5 V version at 5.0±5 % VDC |
| Supply current | 1.95 mA continuous / 1.1 mA single-shot / 115 µA sleep | Size the battery against your sampling strategy |
| Response time | 0.8 to 2.5 ms | A 0.8 ms version is available on request |
| Time to first valid data | 10 to 15 ms | Wait this long after power-on before reading |
| Pressure / temperature resolution | Pressure 0.001 % FS; temperature 0.0079 °C | 24-bit data (1 sign bit + 23 significant bits) |
| Long-term stability | ±0.1 % FS/year (≥1 bar); ±0.2 % FS/year (<1 bar) | Stated separately from TEB |
| Overload capability | ≥3 × FS; up to 4× to 10× on some ranges | Banded by calibrated pressure; see the overload table |
Read the TEB row carefully: it is only meaningful together with its temperature band, and typical and maximum are different commitments. TEB is a combined error band, not the same thing as “accuracy” — writing TEB down as accuracy in a procurement spec is the most common error in this category.
Supply and bus: four checks before power-on
- The sensor does not do level translation. If the MCU runs 3.3 V logic while the sensor is powered at 5 V, or the other way round, the SDA / SCL pull-up level must match VDD. Otherwise communication becomes unreliable or the part can be damaged. Level shifting belongs on the MCU side; do not expect the sensor to adapt.
- Size I²C pull-ups for the actual bus. The product datasheet recommends 10 kΩ; speed, capacitance and device sink-current limits also matter. Use NXP’s I²C specification, section 7.1 and check rise time on the assembled bus.
- Hold the supply tolerance. The 3.3 V version expects 3.3±5 % VDC and the 5 V version 5.0±5 % VDC. Outside that window, accuracy suffers directly.
The datasheet lists reverse-supply and output protection, with applicable limits. Check supply, logic levels, pins and ratings before commissioning. Protection is not permission to miswire the device or exceed its supply rating.
Wiring: pin-out for the four output modes
| Output mode | Red | Black | Green | Blue | White |
|---|---|---|---|---|---|
| Voltage output | V+ | V- | N/C | N/C | Vout |
| I²C + voltage | V+ | V- | SDA | SCL | Vout |
| I²C output | V+ | V- | SDA | SCL | N/C; additional signal pins depend on the selected interface drawing |
| SPI output | V+ | V- | SDI | SCLK | CSB |
The table summarises wire colours for the listed versions; it is not a complete protocol guide. M12 voltage: Pin1 V+, Pin2 Vout, Pin3 V−, Pin4 N/C. M12 I²C: Pin1 V+, Pin2 SCL, Pin3 V−, Pin4 SDA. Obtain the ordered SPI version’s data-line direction, multiplexing, mode and timing documentation before programming; the five-wire table does not define them.
The temperature is media temperature, not ambient
What comes back on the digital bus is media temperature, and the usable range depends on the pressure range: -20 to 80 °C for ranges above 2 bar, -10 to 70 °C for ranges at or below 2 bar. Temperature accuracy is ±2.0 °C with 0.0079 °C resolution.
The temperature channel relates to the medium and thermal coupling at the sensor, rather than cabinet ambient temperature. Mounting, contact and thermal response affect the reading. High-accuracy or fast temperature measurements need a separate suitability check; resolution alone is not accuracy.
Operating temperature, protection and mounting
Where hydraulic shock or water hammer is routine, specify the optional integrated pulse pressure buffer (the W position in the ordering code). Full parameters, the banded overload table and the ordering code are in the datasheets on our downloads page.
FAQ
If I buy the analogue voltage version only, can I still read temperature?
No. The voltage output version carries no temperature signal; temperature is available only over I²C or SPI. If you need temperature, keep a digital port in the specification.
What is the I²C slave address, and can I hang several on one bus?
The 7-bit address is 0x6D; address bytes including the read/write bit are 0xDA and 0xDB. Most MCU APIs expect 0x6D. Isolate equal-address devices with an I²C multiplexer or confirm another interface. Power cycling alone can allow back-power through SDA/SCL and is not a proven isolation method.
Can a 3.3 V MCU talk directly to a 5 V powered sensor?
Not recommended. This sensor performs no level translation: VDD and the SDA / SCL pull-up level must be identical. Either run everything at 3.3 V or add level shifting on the MCU side.
What changes below 1 bar?
The banding changes. At or above 1 bar: long-term stability ±0.1 % FS/year, compensated temperature -20 to 85 °C. Below 1 bar: ±0.2 % FS/year, compensated temperature -10 to 70 °C. Low-pressure ranges have a narrower compensated window, which matters outdoors or where temperature swings are wide.
How long will it run on battery?
Sleep current is 115 µA, single-shot mode 1.1 mA and continuous mode 1.95 mA. Real battery life depends on sampling rate, supply voltage and cell capacity. For long unattended standby, the datasheet notes that a low-power version is available on request.
More answers in the FAQ.
Specifications: View PM160-DV datasheet (PDF) · Download PDF