The Telemecanique (Schneider Electric) TWDAMI8HT is a high-density Analog Input Expansion Module for the Twido PLC range. It is designed to provide a large number of analog sensor connections in a very compact form factor.
The “8” in the model name indicates it features 8 input channels, which is significantly higher than the standard 2 or 4-channel modules found in most micro-PLC systems.
1. Function and Performance
The TWDAMI8HT converts standard industrial analog signals into 12-bit digital values for the Twido CPU to process.
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Input Channels: 8 Non-isolated inputs.
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Resolution: 12-bit (0 to 4095).
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Sampling Time: Approximately 10ms to 20ms per channel depending on the configuration.
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Isolation: There is isolation between the inputs and the internal logic (via photocoupler), but no isolation between individual channels. All 8 channels share a common 0V (COM) reference.
2. Supported Signal Ranges
This “HT” variant is optimized for linear voltage and current signals. It does not support direct temperature sensor connections (like Thermocouples or RTDs).
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Voltage: $0–10V$ DC.
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Current: $4–20mA$.
3. Connection and Physical Layout
Because it squeezes 8 channels into a small space, the wiring interface is dense:
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Terminal Block: It uses a removable screw terminal block (typically 18 to 20 pins).
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Bus Connection: It snaps onto the right side of a Twido Compact or Modular CPU. Up to 7 expansion modules can be added to a single CPU, depending on the base model’s power capacity.
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External Power: Requires an external 24V DC power supply to operate the analog-to-digital conversion circuitry.
4. Technical Specifications
| Feature | Details |
| Model | TWDAMI8HT |
| Series | Twido Expansion (TWD) |
| Input Impedance | Voltage: $\geqslant 1 M\Omega$ / Current: $250 \Omega$ |
| Measurement Error | $\pm 0.2\%$ of full scale at $25°C$ |
| LSB (Resolution) | $2.44 mV$ (for $0-10V$) / $3.91 \mu A$ (for $4-20mA$) |
| Software | TwidoSoft or TwidoSuite |
5. Key Considerations
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Twido Legacy: The Twido line is now a Legacy product. Schneider Electric recommends the Modicon M221 as the modern replacement. If you are replacing a failed TWDAMI8HT in a new system, you would likely use the TM3AI8 module (though these are not physically compatible with old Twido CPUs).
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Grounding: To ensure accuracy with 8 channels sharing a common ground, it is critical to use shielded cables and ground the shield at a single point (usually at the PLC end) to prevent noise from jumping between channels.
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Addressing: In TwidoSuite, these inputs are addressed as
%IW0.x.y(where $x$ is the position of the module and $y$ is the channel number).












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