Safety integrity and fail-safe operation
The Siemens 6ES7326-1RF01-0AB0 is an SM 326 fail-safe digital input module with 8 inputs at 24 VDC, rated for safety applications up to SIL 3 (two-channel) per IEC 61508, PLe per ISO 13849-1, and Category 4 per EN 954-1 — the highest performance level for safety-related control systems. Fail-safe operation is enabled by design, with parameterizable diagnostic alarms and a group error SF (red) indicator for fault annunciation.
Intrinsically safe Ex(i) inputs
This module supports Ex(i) intrinsic safety protection. The output voltage is 8.2 V DC with a maximum power output of 33.1 mW. Maximum permissible external capacitance is 3 µF and inductance 80 mH at the intrinsically safe terminals, with reverse polarity protection included.
The closest functional replacement would need to match the 8 fail-safe inputs, 24 VDC rating, Ex(i) intrinsic safety, and SIL 3 / PLe / Cat. 4 safety integrity — verify the specific BOM position before substituting.
The module occupies a standard slot with dimensions 80 mm wide, 125 mm high, and 120 mm deep. It requires a 40-pin front connector for field wiring. Maximum cable length is 200 m shielded or 100 m unshielded. Input signal delay from 0 to 1 and 1 to 0 is 1.2 to 3 ms maximum, with a signal "1" current draw of 2.1 to 7 mA.