Description
The Siemens 6ES7231-4HD32-0XB0 is a high-density SIMATIC S7-1200 SM 1231 analog input signal module. This hardware expansion module adds 4 differential analog input channels to a host S7-1200 CPU station, allowing direct interfacing with industrial process instrumentation such as temperature transmitters, pressure transducers, and flow meters.
Commercial and Logistics Details
- Product Condition: New Original (Factory Sealed)
- Warranty Period: 12 Months
- Standard Lead Time: 1–2 business days from order confirmation
- Pricing Note: Unit pricing is subject to local distributor allocations and project volume tier discounts; contact our industrial automation desk for a firm, formal quote.
Technical Architecture & Field Deployment Notes
In field deployments of S7-1200 automated systems, the 6ES7231-4HD32-0XB0 module is mounted directly to the standard DIN rail on the right-hand side of the CPU, connecting via the integrated slide-out bus connector.
Signal Configuration and Filtering
Each of the 4 channels is independent and can be configured via TIA Portal to accept either \pm10 V, \pm5 V, \pm2.5 V, or standard 0 to 20 mA / 4 to 20 mA signals. Note that when processing low-level 4 to 20 mA instrument loops, the module utilizes a 12-bit + sign resolution, mapping the nominal scale to an internal integer range of 0 to 27648.
Commom-Mode Voltage and Grounding
When wiring long-distance field transmitter cables (exceeding 100 meters), common-mode voltage differences (U_{CM}) between the field grounds and the PLC rack ground can distort the ADC measurements.
- Best Practice: Connect the negative input terminals (M-) of unused channels directly to the main system ground (M) to prevent erratic open-circuit floating voltage errors in your TIA Portal diagnostic buffer.
- Shielding: Terminate cable shields using a low-impedance grounding clamp directly onto the shield-bonding bar at the entrance of the control panel housing.
Technical Specifications
| Parameter | Value |
| Brand | Siemens |
| Product Family | SIMATIC S7-1200 |
| Model Number | SM 1231, AI 4 x 13 Bit |
| Part Number | 6ES7231-4HD32-0XB0 |
| Number of Inputs | 4 (Differential) |
| Voltage Input Ranges | \pm10 V, \pm5 V, \pm2.5 V |
| Current Input Ranges | 0 to 20 mA, 4 to 20 mA |
| Resolution | 12 bits + sign bit (13-bit total) |
| A/D Conversion Time | 625 \mus per channel |
| Input Impedance | Voltage: \ge 9 M\Omega, Current: 250 \Omega |
| Isolation | 500 V AC between analog circuits and internal logic bus |
| Current Consumption | 45 mA from 5 V DC backplane; 85 mA from 24 V DC auxiliary supply |
| Power Loss | 1.5 W |
| Dimensions (W x H x D) | 45 mm x 100 mm x 75 mm |
Frequently Asked Questions
Can this module supply loop power directly to a 2-wire transmitter?
No. The 6ES7231-4HD32-0XB0 is a passive measurement receiver module. For 2-wire transmitters, you must route an external 24 V DC loop power supply in series with the transmitter instrument and the module’s input terminals. For 4-wire transmitters, the instrument provides its own powered output directly into the module.
How do I clear an “Overflow/Underflow” diagnostic fault in TIA Portal?
An underflow fault typically triggers on a 4 to 20 mA loop configuration if the physical current drops below 3.6 mA (often indicating a physical wire break or a failed transmitter). An overflow fault occurs if the incoming signal transcends the maximum scale (>22.8 mA or >11.85 V). Inspect the loop current with a standard multimeter inline to verify physical loop health.
What is the maximum distance supported for analog input cabling?
Siemens recommends a maximum length of 100 meters using twisted-pair, shielded instrumentation cable. Exceeding this line distance increases line resistance and capacitive coupling noise, which may require you to increase the hardware smoothing/filtering level within the module configuration properties in TIA Portal.
