Channel-Granular vs Module-Granular Passivation for Fail-Safe and High-Availability Modules in PCS 7 V7.0

In SIMATIC PCS 7 V7.0 high-availability and fail-safe automation architectures, passivation behavior defines how the system responds when an I/O channel faults. Under CPU 'H-Parameters' and F-Configuration, passivation can be configured as channel-granular (Kanalgranular) or module-granular (Modulgranular). For fail-safe analog module 6ES7336-4GE00-0AB0 (F-AI 6x15Bit HART), channel-granular passivation is supported using S7 F Systems V6.0, allowing healthy safety channels to operate while passivating only the faulted sensor. For standard redundant HART modules 6ES7331-7TF01-0AB0 (AI 8x16Bit) and 6ES7332-8TF01-0AB0 (AO 8x16Bit), channel-selective evaluation is supported when deployed on active bus modules with the PCS 7 Redundant I/O Library.

Core Concepts: Channel-Granular vs Module-Granular Passivation

In high-availability (S7-400H) and safety-instrumented (S7 F Systems) architectures, sensor or field wiring faults require deterministic fault mitigation, known as passivation. Passivation ensures that corrupted process data is instantly substituted with safe fallback values (e.g. 0 mA or configured fail-safe substitute values):

Module-Granular Passivation (Modulgranular): When a fault (wire break, short circuit, or ADC error) occurs on a single channel, the operating system passivates the entire physical module. All channels on the card are taken out of service, even if the remaining channels are completely healthy.
Channel-Granular Passivation (Kanalgranular): The operating system isolates and passivates strictly the individual faulted channel. All remaining healthy channels on the module continue active cyclic process operation without interruption.

In continuous chemical and process plants, channel-granular passivation is overwhelmingly preferred to prevent unnecessary trips of multiple unrelated process loops sharing the same physical I/O card.

Passivation Support Matrix for HART and Fail-Safe Modules in PCS 7 V7.0

In SIMATIC PCS 7 V7.0 and V7.0 SP1, module firmware and software library versions dictate exact passivation capabilities:

Module DesignationOrder Number (MLFB)Module ClassificationPassivation Behavior in PCS 7 V7.0Configuration PrerequisiteSM 336 F-AI 6x15Bit HART6ES7336-4GE00-0AB0Fail-Safe Safety (SIL 3)Channel-Granular supportedS7 F Systems V6.0+, F_CH_AI driver blockSM 331 AI 8x16Bit HART6ES7331-7TF01-0AB0Standard / Redundant AIChannel-Granular supportedActive backplane bus, RedLib V3.0+SM 332 AO 8x16Bit HART6ES7332-8TF01-0AB0Standard / Redundant AOModule / Channel-SelectiveActive backplane, RedLib redundant pairing

For standard redundant I/O, the active backplane bus module (6ES7195-7HD10-0AA0) allows hot swapping of individual modules without disrupting neighboring cards.

Configuring Passivation in HW Config and S7 F Systems

To configure channel-granular passivation properly in SIMATIC PCS 7 V7.0, execute the following technical workflow:

Fail-Safe Module Configuration (SM 336-4GE00):
- In HW Config, double-click the 6ES7336-4GE00-0AB0 module.
- Under the F-Parameters tab, locate Passivation behavior.
- Select 'Channel-granular' (Kanalgranular). Enable wire-break and diagnostic interrupts for each active sensor loop.
- In CFC, place the fail-safe channel driver F_CH_AI from the S7 F Systems library. Interconnect PASS_OUT to monitor channel passivation status, and interconnect ACK_REI for operator reintegration.
Standard Redundant HART Modules (SM 331 / SM 332):
- In HW Config, configure redundant pairs of modules across separate ET 200M stations.
- Open CPU Properties -> H-Parameters tab. Verify that redundant I/O monitoring is enabled.
- In CFC, utilize the PCS 7 Redundant Library channel driver blocks (CH_AI / CH_AO or RED_AI / RED_AO). The driver automatically tracks individual channel discrepancy and passivates only the defective half-channel while maintaining process control on the redundant partner channel.

Verification

Verify correct passivation and reintegration behavior through these diagnostic tests:

Induce Wire Break on Channel 0: Disconnect field wire on channel 0 of the 6ES7336-4GE00-0AB0 module.
Channel-Granular Isolation Check: Verify in CFC online test mode that channel 0 driver F_CH_AI.QBAD transitions to 1 (passivated), while channels 1 through 5 maintain QBAD = 0 with live valid process readings.
Channel Reintegration: Reconnect the field wire. Verify that toggling ACK_REI (or clicking Reintegrate on the safety faceplate) clears QBAD and restores normal signal processing without CPU restart.

Limitations and Operational Precautions

When engineering passivation behavior in PCS 7 V7.0, observe these critical safety and operational rules:

Version Sensitivity: In PCS 7 V7.0 base release, channel-granular passivation for certain fail-safe modules required specific F-Configuration Tool updates. Always ensure S7 F Systems V6.0 SP1 or higher is installed.
Substitute Value Selection: In fail-safe loops, verify whether SUBS_V (substitute value) is configured for zero, last valid value, or a specific safe default, matching the Safety Requirement Specification (SRS).
Commercial Accuracy Notice: Fail-safe modules and runtime packages require dedicated S7 F Systems licenses and safety coprocessor capacity. Verify all order numbers (MLFBs) against current Siemens catalogs and authorized distributor quotations.

Engineer FAQ

What happens if an F-module is set to module-granular passivation?

If set to module-granular passivation, a single wire break on channel 0 forces all 6 channels into passivation, outputting substitute values on all safety loops connected to that card.

Why can some older analog modules only support module-granular passivation?

Older S7-300 modules lacked per-channel ADC converters and internal diagnostic ASICs; they utilized a single multiplexer that could only report faults for the entire board.