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Why is the sensor not detected by the display or data logger?

by | May 19, 2026 |

If a sensor is not detected, the issue is usually related to power supply, physical connection, addressing, protocol configuration, or system overload when multiple sensors are involved.
Possible causes:
  • The sensor is not receiving the required supply voltage.
  • Communication wiring is incorrect, loose, or damaged.
  • The selected interface or protocol does not match the connected device.
  • Modbus address, baud rate, parity, or network settings are incorrect.
  • Cable length, shielding, or topology does not meet the communication requirements.
  • Multiple sensors are drawing excessive current and exceeding the power supply rating.
Systematic diagnostic approach:
  • Test sensors individually – disconnect all sensors from the display or data logger and connect them one at a time. This isolates whether the problem is a single faulty sensor, a configuration issue, or a system-level power/addressing conflict.
  • Measure supply voltage directly at sensor terminals – verify the sensor is receiving the required voltage under load; inadequate voltage is a common cause of non-detection.
  • Verify wiring against the device manual – confirm correct polarity, wire gauge, and communication line assignment; use only the specified cable type (e.g., 2-pole twisted pair for Modbus).
  • Check address and communication parameters – verify Modbus address, baud rate, parity, and network settings match the sensor configuration and display/data logger settings.
  • Inspect cable condition and compliance – ensure cables meet shielding and twisted-pair specifications for the communication protocol; test with a short known-good cable in a simple setup to rule out cable issues.
  • Review power supply ratings – if multiple sensors are connected, verify that the total current draw does not exceed the display or data logger power supply rating. Excessive load can prevent sensor detection or cause intermittent operation.
  • Check bus system configuration – for multi-sensor bus systems (Modbus, etc.), inspect termination resistors, grounding concept, line polarity, and topology.

Why are measurement values missing in the data logger?

by | May 19, 2026 |

Missing logged values usually mean the logger is not consistently receiving, storing, or mapping the measurement data. The cause depends on whether data was never logged or whether logging suddenly stopped.
Possible causes:
  • The channel is not configured correctly in the logger or the sensor was removed from the logging configuration.
  • Logging interval, memory handling, or trigger settings are incorrect.
  • Communication to the sensor is intermittent or has been interrupted.
  • Power supply interruptions or failures affect the logger or sensor.
  • The selected variable is displayed live but not assigned correctly for recording.
  • Physical cable connection has degraded or been accidentally disconnected.
Diagnostic approach for data that suddenly stopped:
  • Check recent system changes – ask whether anyone has modified, serviced, or reconfigured the system recently; check if cables were unplugged or equipment was moved.
  • Verify power supply to the sensor – confirm that supply voltage is still present at the sensor terminals; power loss is a common cause of sudden data loss.
  • Test the physical cable – inspect the communication cable for damage, looseness, or degradation; test with a known-good cable to rule out cable failure.
  • Review logger configuration changes – check whether the sensor was accidentally removed from the logging assignment or whether channel mapping was altered.
  • Review timestamps – identify whether gaps in logged data coincide with power interruptions, communication dropouts, or known system maintenance events.
Diagnostic approach for configuration-related issues:
  • Verify channel mapping, tag assignment, and recording parameters – ensure the sensor is correctly assigned to a data logger channel and that recording is enabled.
  • Check communication status – review the logger diagnostic menu for communication errors or sensor dropouts.
  • Confirm storage and memory – verify that the storage medium and memory capacity are functioning correctly and have not reached capacity limits.
  • Test with a shorter interval and stable connection – use a shorter logging interval with direct connection to the logger to confirm whether the issue is configuration-related or hardware-related.
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