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2026-09-14
The CLM223 is a panel-mounted conductivity transmitter from the Endress+Hauser Liquisys M series, typically paired with CLS series conductive or inductive sensors. Many field engineers are initially baffled by this "little blue-screened box" and its nested menu structure (Setup 1 / Setup 2 / Output). This article outlines the commissioning process in a logical sequence—from wiring checks and menu access to conductivity parameters, temperature compensation, current output configuration, and final calibration/start-up—to help you get it running smoothly on the first try.
Pre-commissioning essentials: Have the sensor's factory calibration certificate (which lists the cell constant) and a small flat-head screwdriver ready. Before changing any parameters, record the existing settings; while the "S9 = Facty" option in the Service menu allows for a factory reset if things go wrong, doing so will erase all your custom configurations.
The terminal block layout for the CLM223 is clearly defined in the official manual; be sure to verify connections against the diagram before commissioning:
The instrument is a Class II device and generally does not require a protective earth connection; however, the conductive sensor's cable shield *must* be connected to the PE terminal to prevent measurement interference.
The CLM223 operating unit features only three keys: E (ENTER/Confirm), + (Plus/Scroll Down), and − (Minus/Scroll Up). Press + and − simultaneously to exit the current menu.
This is the core parameter group; it determines "what is measured" and "how it is displayed."
Press the − key to navigate to SETUP 2, press E to enter, select B1 Pt100, and press E to confirm; this enables automatic temperature compensation.
Key Concept: The α value in B3 (default 2.10 %/K) and the reference temperature in B7 (default 25 °C) are distinct concepts. α represents the "percentage change in conductivity per 1°C rise," while the reference temperature is the "baseline temperature to which compensation is applied." Changing B7 does not affect α, and vice versa. Temperature Sensor Calibration Procedure:
If the real-time temperature displayed in B5 differs from the reading on an independent field thermometer, enter the actual measured value from the external thermometer into B5 and press E; the instrument will automatically calculate the offset and store it in B6. This step is crucial for long-term accuracy.
After configuring temperature compensation, press the − key to enter the OUTPUT function group:
After configuring one channel, if the instrument supports dual-channel output, switch from OUT1 to OUT2 and repeat the steps above to output the temperature as a 4–20 mA signal as well.
Tip for range setting: The values for 0312/0313 do not necessarily have to correspond to "0 to full scale"; they can be scaled to the 4–20 mA range based on the actual process interval, resulting in higher display resolution at the DCS end.
Conductivity sensors typically do not require field calibration (the cell constant is calibrated at the factory; simply enter the value from the certificate into A5); however, inductive sensors must undergo an "Air Set" calibration in air:
Once calibration is complete, press the + and − keys simultaneously to return to the measurement interface.
The CLM223 supports alarm contact functions. Within the "Alarm" function group, you can configure alarm limits, hysteresis, and relay switching logic. Specific configuration depends on on-site interlocking requirements; generally, default settings are sufficient. If a fault occurs, a red alarm indicator lights up on the panel; refer to Chapter 8, "System Error Messages," in the manual to troubleshoot.
If parameters have been incorrectly altered or the instrument needs to be repurposed:
Before restoring factory settings, be sure to record critical parameters such as A5 (cell constant) and O312/O313 (measurement range). Otherwise, you will have to re-enter them from memory after the reset, and measurement accuracy cannot be guaranteed.
→ Usually caused by inorganic scaling/fouling on the electrode. Soak the electrode in a 1:10 diluted hydrochloric acid solution for 30 minutes, then rinse with deionized water; also, verify that the cell constant (A5) matches the value on the calibration certificate.
→ Typical power-frequency interference. Check that the cable shield is securely crimped at the terminal block; install a ferrite bead filter (100 MHz) if necessary.
→ Go to B5 in Setup 2, compare the reading with an external precision thermometer, and perform an offset adjustment using B6.
→ Check if the range limits set in O312/O313 match the range configured in the DCS; confirm that O1 is set to Out1 rather than Out2.
→ This is by design: B3 is only active when B2 is set to "lin" (linear). When NaCl, Pure, PureH, or Tab is selected, internal compensation curves take over, and the α setting no longer applies.
The CLM223 menu structure may appear complex, but it essentially follows a three-step process: "Setup 1" defines the measurement, "Setup 2" defines the temperature settings, and "Output" defines the measurement range. As long as the cell constant, temperature compensation method, and range mapping are configured correctly, the rest is just fine-tuning. Taking a photo of the original values before changing parameters is the most cost-effective "insurance" for a field engineer.
If you are using the device with a CLS21 conductivity sensor, the default combination—"cond" mode + Pt100 + "lin" + α=2.10%/K + reference temperature 25°C—meets the requirements for the vast majority of industrial water quality monitoring applications. You only need to switch to the specific NaCl, Pure, or PureH compensation curves when dealing with special media (such as high-concentration NaCl, ultrapure water, or mixed solutions of acids, bases, and salts).
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