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Asked:18 Oct 2025

SIMATIC S7-400 / S7-400H / S7-400F /FH: S7-400h Platform trouble Including the Continuous Signal inputs

Hi i use S7-400H system (CPU414-H= 6ES7 414-4HM14-0AB0) with analog AI 431-0HH00-0AB0. The digital I/Os work fine, but I have trouble with the analog inputs.
I use 4..20mA 2 wire transducers sitrans th100. I configured the AI Modules as 2DMU and set range selector on the side of the module as 2-wire.
I also set in properties PLC "size of the process-image input area" to 2048/
I measured by multimeter - 6mA. But in modul i see 32767(DEC)
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Analog Input Connection in S7-400H
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#sosflex #SIMATIC S7-400 / S7-400H / S7-400F /FH #siemens
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Answers(1)
Siemens Test Added an Answer on18 Oct 2025

Analog Input Issue with S7-400H and AI 431-0HH00-0AB0

It appears you're experiencing issues with your analog inputs on the S7-400H system despite functional digital I/Os. Here's a breakdown of potential causes and troubleshooting steps, considering your Sitrans TH100 4-20mA transducers and AI 431-0HH00-0AB0 module configuration.

Possible Causes & Solutions:

  • Wiring: Double-check the wiring between the transducers and the AI module. Ensure correct polarity (+/-) and a proper 2-wire connection.
  • Module Configuration: Verify the AI module's hardware configuration (jumper settings) matches your 2-wire transducer setup.
  • Scaling: The value of 32767 (DEC) typically indicates a saturation point, possibly due to incorrect scaling in your PLC program. Review your scaling calculations based on the 4-20mA input range.
  • Hardware Fault: While less common, a faulty AI module or transducer could be the issue. Try swapping components if possible.
  • PLC Parameterization: Ensure the "size of the process-image input area" (2048) is appropriate for your application and doesn't conflict with other module assignments.

Further Resources:

For detailed information on configuring and troubleshooting the AI 431-0HH00-0AB0 module, please refer to the following resources on SiePortal:

If the problem persists, please provide your PLC program section related to analog input handling for further assistance.

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