Checking Measuring Instrument Functions and Simulating Sensor Signals

Reliable measurement results require not only correctly functioning sensors but also properly operating measuring instruments. If implausible measurement values or deviations occur, it is necessary to determine whether the cause lies in the sensor or in the signal processing of the measuring instrument.

The HORIBA X-51 Digital Simulator is a testing instrument designed to simulate defined electrical sensor signals. It enables functional testing of compatible measuring instruments without requiring an actual measurement signal from a water sample.

The simulator generates electrical substitute signals for the measurement parameters pH, oxidation-reduction potential (ORP), ion-selective measurement (ION), dissolved oxygen (DO) and temperature (TEMP). This makes it possible to check the response of a measuring instrument to predefined input signals and verify important signal processing functions.

One of the main applications is the regular functional testing of measuring instruments. The HORIBA X-51 particularly supports the verification of linearity and temperature compensation functions.

Unlike a water analysis instrument, the simulator does not directly measure water parameters in a sample. Instead, it provides defined electrical input signals that can be used to check the behaviour of a connected measuring instrument.

This makes the HORIBA X-51 particularly suitable for servicing, technical troubleshooting, regular instrument inspections and quality assurance in measurement technology.

Simulated Measurement Parameters of the HORIBA X-51

The digital simulator provides different electrical substitute signals for testing compatible measuring instruments. The type of output signal depends on the respective measurement parameter.

• pH Value: Simulation of a corresponding electrode voltage signal to verify the pH measurement function.
• Oxidation-Reduction Potential (ORP/mV): Output of defined voltage signals to check mV measurement and signal processing.
• Ion-Selective Measurement (ION): Simulation of electrical voltage signals from ion-selective electrodes to test compatible ion measuring instruments.
• Dissolved Oxygen (DO): Provision of an electrical substitute current signal for testing corresponding dissolved oxygen measuring instruments.
• Temperature (TEMP): Simulation of a temperature-dependent resistance signal corresponding to the behaviour of a thermistor.

The simulated signals are used to verify the electrical inputs of measuring instruments and their associated evaluation functions. They do not replace measurements of actual water samples or comprehensive testing of connected sensors.

Functions and Features

Simulation of Defined Electrode Voltage Signals

For pH, ORP and ion-selective measurements, the HORIBA X-51 provides electrical substitute voltage signals. These correspond to theoretical input signals of the respective electrodes.

The connected measuring instrument can therefore be supplied with predefined signals. By evaluating the displayed values, it is possible to determine whether the signal processing operates within the specified test criteria.

Current Signal for Dissolved Oxygen Measurement

To test the dissolved oxygen measurement function, the simulator generates an electrical substitute current signal. This allows the behaviour of compatible dissolved oxygen measuring instruments to be examined independently of an actual water sample.

The simulation helps distinguish between possible faults in the sensor unit and problems with processing the electrical input signal.

Simulation of Temperature-Dependent Resistance

For temperature testing, the HORIBA X-51 provides an electrical substitute resistance corresponding to the signal of a thermistor.

This allows the temperature measurement function and temperature-dependent calculations of compatible measuring instruments to be checked.

Verification of Linearity

Linearity describes how consistently a measuring instrument responds to different input signals within its specified measuring range.

With the HORIBA X-51, defined test signals can be applied and compared with the displayed measurement values. This supports the identification of possible deviations in signal processing.

Checking Temperature Compensation

In various electrochemical measurement methods, temperature influences the calculation of measurement values. For this reason, corresponding measuring instruments feature temperature compensation functions.

The HORIBA X-51 supports the verification of these functions by simulating suitable electrical input signals.

Support for Troubleshooting

If implausible values are displayed during water analysis, several possible causes must be considered. These may include contaminated or damaged sensors, connection problems and faults in the measuring instrument electronics.

By applying a defined substitute signal, it is possible to check whether the measuring instrument processes this signal as expected. This helps systematically narrow down potential sources of error.

For Regular Functional Testing

The digital simulator can be used for recurring inspections to check the behaviour of compatible measuring instruments using defined input signals.

The evaluation of test results is based on the technical specifications of the respective measuring instrument and the applicable testing procedures.

Typical Applications

The HORIBA X-51 is suitable for various testing and service tasks in electrochemical measurement technology.

• Laboratory Analysis: Functional testing of compatible pH, ORP, ion and dissolved oxygen measuring instruments.
• Service and Maintenance: Verification of electrical signal processing during regular instrument inspections.
• Technical Troubleshooting: Identification of possible causes of implausible or deviating measurement displays.
• Quality Assurance: Support for documented functional testing of measuring instruments.
• Linearity Testing: Comparison of predefined electrical input signals with displayed measurement values.
• Temperature Compensation: Verification of temperature-dependent measuring instrument functions.
• Technical Customer Service: Systematic testing of compatible measuring instruments during maintenance and service work.
• Research and Development: Support for functional testing of suitable electrochemical measurement systems.

Advantages of Digital Sensor Simulation

• Simulation of electrical sensor signals for pH, ORP, ION, DO and temperature.
• Testing of compatible measuring instruments without an actual water sample.
• Support for verifying measuring instrument linearity.
• Checking temperature compensation functions.
• Systematic identification of possible error sources in signal processing.
• Suitable for regular functional testing and technical service work.
• Support for traceable documentation of test results.
• Multiple simulation functions combined in one testing instrument.

Technical Information and Downloads

The HORIBA X-51 Digital Simulator is designed to simulate theoretical electrical input signals for compatible measuring instruments.

Substitute voltage signals are provided for pH, ORP and ion measurements, substitute current signals for dissolved oxygen measurements, and corresponding substitute resistance signals for temperature measurements.

Information on the available simulation ranges, connection options, operating functions and testing procedures can be found in the instruction manual in the download section.

Before use, check the compatibility of the simulator with the respective measuring instrument, as well as the required connections and testing specifications.

Note on Use: The HORIBA X-51 is a simulator designed to verify electrical measuring instrument inputs and associated evaluation functions. It does not replace the calibration and maintenance of actual sensors or any comprehensive metrological verification of the measurement system that may be required.

Note on Scope of Delivery: From November 2026, HORIBA products will be supplied without batteries. Existing stock may still include batteries. Batteries are no longer included with newly manufactured products and must be purchased separately if required.