Analog input module | 1xJ/K thermocouple | 24VDC | 6ES7231-5QA30-0XB0 Siemens

Technical specifications
Product: SB 1231 AI 1×16 bit TC
Power supply: 24 V DC
Current consumption: 5 mA (typ.), from PLC bus 20 mA (typ.)
Max. power loss: 0.5 W
Analog inputs: 1 (thermocouples)
Compatible thermocouple types: J (up to 1200 °C), K (up to 1372 °C), also T, E, R, S, B, N, C, TXK/XK(L)
Voltage range: ±80 mV
Input resistance: ≥1 MΩ
Resolution: 15 bits + sign
Accuracy: ±0.1 % (at 25 °C), ±0.2 % (up to 55 °C)
Interference suppression: ≥85 dB (10 / 50 / 60 / 400 Hz)
Diagnostics: wire break, error signaling, LED indication
Ambient temperature: -20…+60 °C (horizontal), -20…+50 °C (vertical)
Humidity: up to 95 % non-condensing
Dimensions: 38 × 62 × 21 mm
Weight: ~35 g
Certificates: CE, UL, CSA, cULus, FM, RCM, KC, Marine approval

Functions

Direct temperature measurement from thermocouples.

High accuracy class with ±0.1 % error.

Integrated diagnostics and alarm system – wire break detection, error LED indication.

Supports various thermocouple types, making the module versatile for different industrial applications.

Compact size – easy integration into SIMATIC S7-1200 system.

Application

For engineers: ensures reliable temperature control in production processes, energy, heating, ventilation, and air conditioning (HVAC) systems.

For electricians: easy to install in existing S7-1200 PLC, clear connection system, diagnostic LED indicators simplify commissioning and maintenance.

For industry: ideal for chemical, pharmaceutical, food, and metal processing sectors requiring precise temperature measurement.

Pros

Compact and lightweight (only 35 g).

High compatibility – supports multiple thermocouple types.

High accuracy and stability even under interference.

Integrated fault diagnostics and LED indication.

Reliability – CE, UL, CSA, marine certificates.

Cons

Only one analog input (limited channels).

Requires SIMATIC S7-1200 system – cannot work standalone.

Not suitable for current or resistance sensors (only thermocouples and ±80 mV voltage measurement).