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Support Center: Guides & FAQs

Find guidance on installation, product selection, technical concepts, and troubleshooting.

This Knowledge Base provides clear answers about compressed air monitoring and SUTO iTEC products. Topics include installation, choosing the right instruments, and solving common issues. We update this section regularly with new content. If you cannot find the information you need, please contact us.

Customer Support

Troubleshooting & Maintenance (2)

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Why is my flow meter not detected?

Modbus communication problems are often caused by wiring errors, wrong address settings, reversed lines or unstable power supply.

Possible causes:
  • The wiring might be incorrect or the cable could be damaged.
  • The Modbus communication lines (D+ and D−) may be reversed.
  • If you’re using Modbus TCP, the sensor might be connected directly to a PC instead of through a network switch or hub.
  • The configured Modbus address might not match the sensor’s actual address.
  • The sensor may not be powered or the supply voltage could be too low.
Solutions:
  • Compare the wiring with the sensor’s user manual to ensure all connections are correct.
  • Use a multimeter to check for a stable 24 VDC power supply.
  • Test the cable for continuity or try a known working replacement cable.
  • Verify the Modbus address and communication settings using the S4C-FS configuration software.
  • Ensure the cable from the splitter to the sensor is shorter than 30 cm for proper detection.
  • Use the S4C-FS software’s address scan function to detect the sensor on the network.
Tags: detection error, device not detected, flow meter not found, no Modbus connection, no signal, S401, S415, S418, S421, S430, S451, S453, sensor startup, wiring issue
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Why is the sensor not detected by the display or data logger?

Sensors that are not detected are commonly caused by power supply issues, incorrect wiring, communication mismatches, or overloaded systems.

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.
Tags: data logger, detection error, display
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