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I. How to determine whether the measuring probe of a sonar-type external level gauge is functioning properly? 1. The resistance of the probe’s positive and negative terminals is 400 KΩ ±5%; if it is not within this range, it indicates a hardware fault with the probe or an issue with its wiring. 2. Remove the probe, bring your ear close to the probe core; a clicking sound is produced when the probe is in operation. 3. Visually inspect the probe core for any cracks or other damages. II. How to determine whether the host hardware is functioning properly? 1. For explosion-proof types (ELL-FI-AE/BE/CE/PE), the normal total current of the device is within the range of 110–170 mA; otherwise, it is considered that there is a problem with the hardware of the main unit. 2. For intrinsically safe types (ELL-FI-CI), the normal current of the entire device is within the range of 4–20 mA; otherwise, it is considered that there is a problem with the hardware of the main unit. Note: The method for measuring the current of the entire device involves connecting an ammeter in series with the power supply circuit; the current value changes at the moment power is applied. III. How to determine that a weak level signal is caused by the loss of coupling agent in the level probe? By pressing the magnetic pen sensor once, the gauge displays a two-digit number ranging from 0 to 85; the higher the value, the weaker the liquid level signal. If the current liquid level is not at the highest level and the maximum displayed value is 85, it is necessary to clean the probe surface again and apply coupling agent. IV. What to do if the instrument freezes? It is necessary to reset the instrument by using a magnetic pen to trigger the gear button twice, or by turning off the power and then turning it back on. V. What checks should be done if the power supply screen goes black? 1. Check whether the no-load voltage is within the normal range (20-32V). If the power supply is abnormal, check whether the power supply lines and modules are functioning properly. 2. Measure the current of the entire device (by connecting an ammeter in series to the power supply terminal of the device) to ensure it is within the acceptable range (110–170 mA). If the current is not normal, please contact customer service to have the hardware replaced. VI. How to handle values displayed as LO or in the vicinity of the blind zone on the instrument? 1. If the tank is empty or the liquid level is below the set value for the blind zone (parameter 2#), it is normal to see LO or a value near the blind zone; no action is required at this time. Normal measurement can be resumed once the liquid level rises. 2. If the actual liquid level is higher than the set value for the blind zone, it is likely that the signal from the blind zone at the probe’s installation location is high; in this case, modify parameter 2# by setting it to a higher value, although the maximum value should still be lower than the actual liquid level. If the LO state still cannot be eliminated, try reinstalling the probe or changing its installation location. VII. How to deal with display deviations in sonar-type external level gauges? 1. If it is a fixed deviation, adjust the migration amount (parameter 3) according to the actual deviation size. 2. If it is a non-fixed deviation, such as a small deviation for low liquid levels and an increasing deviation for high liquid levels, first modify the liquid property coefficient (parameter 6#). It is necessary to raise the liquid level above the calibration probe, and the instrument will automatically calibrate itself. 3. Remote transmission deviation: This refers to the situation where the display on site shows consistency, but there is a deviation in the display in the control room. It is usually caused by differences in range settings. It is necessary to verify whether the range settings are consistent. 4. Level doubling: The level gauge shows the level as an integer multiple of the actual level, usually twice; for example, if the actual level is 1 meter, the gauge will display around 2 meters. This situation generally occurs during the feeding of empty tanks or when the liquid level is low. Issues that occur during feeding can be resolved through the instrument’s automatic reset function; manual reset can be used if necessary. If doubling occurs at a low position and manual reduction is ineffective, try changing the probe installation location. VIII. The sonar-type external level gauge displays a moving short bar; that is, only a black bar moves back and forth in the display area. 1. An empty tank or a liquid level below the blind zone is a normal phenomenon and requires no action. 2. The moving bar is still displayed when the liquid level exceeds the blind zone value. a. Open the junction box to check whether the probe wires are loose. b. After ensuring the wiring is correct, remove the measurement probe and bring its surface close to the ear to listen for any sound; if a sound is heard, the instrument is working properly. c. It may be that the signal is currently too weak; measures such as reinstalling the probe or changing its installation location can be taken. If the probe makes no sound, it may be due to a hardware issue with the instrument; please contact Dinghua Electronics’ customer service.