Hazardous-Area Analog Input Module — Ex(i) Rated
The Siemens 6ES7331-7TB10-0AB0 is a 2-channel analog input module for the SIMATIC S7-300 family, designed for intrinsically safe (Ex(i)) signal acquisition in hazardous locations. It carries ATEX II 3 G (2) GD Ex nA [ib Gb] [ib IIIC Db] IIC T4 Gc and FM Class I, Division 2, Groups A, B, C, D T4 / Class I, Zone 2, Group IIC T4 markings — confirming it for Zone 2 gas and Division 2 classified areas per IEC 60079 and NEC 500. The module accepts 4-20 mA and 0-20 mA signals, with a 50 Ω input resistance and short-circuit proof output limited to approximately 30 mA.
Integration and Wiring Constraints
The module occupies a 40 mm wide slot in the S7-300 DIN rail assembly, with a 125 mm height and 120 mm depth. It requires a 20-pin front connector (sold separately). The maximum shielded cable length is 400 m. Power draw is 4.5 W typical from the 24 V DC backplane bus. The sigma-delta measurement principle supports integration times of 2.5 / 16.67 / 20 / 100 ms, selectable per channel.
Diagnostics and Approvals
Diagnostics are parameterizable, with a group error SF (red) LED, per-channel fault indicator F (red), overrange red LED, and a green HART communication active LED. Channel-to-channel isolation is 2 500 V DC; between inputs the permitted potential difference (UCM) is 60 V DC / 30 V AC. Approvals include CE, UL, KC, EAC, RCM, and ATEX/FM for hazardous locations. Operating range is 0 °C to 60 °C.