Fail-safe signal modules

F digital/analog modules


The fail-safe signal modules of ET 200M are the interface between the fail-safe SIMATIC PLCs and the process. A host of different digital and analog modules provide exactly the inputs/outputs required for each task.


The spectrum of fail-safe input and output modules is used for central expansion of the SIMATIC S7-300F or for distributed expansion in an ET 200M station for fail-safe S7 PLCs.

For distributed expansion of a SIMATIC S7-400FH, the ET 200M I/O also supports a redundant configuration.
In combination with the redundant PROFIBUS interface, this forms the basis of Flexible Modular Redundancy™ (FMR): The fault tolerance level can be tailored to requirements in that single, two and three-channel redundancies can be combined in the same system and tuned to each other. The redundant architecture offers maximum availability since this measure can compensate for failure of a CPU, a PROFIBUS line or a signal module. In addition, safety-related and standard I/O modules (critical and non-critical I/Os) can be combined in an ET 200 M/S station.


  • Space-saving assembly due to the high packing density of channels

  • Easy parameterization in STEP 7

  • Fail-safe and standard modules can be combined

  • One bus (PROFIBUS DP) for the transmission of fail-safe and standard signals

  • Flexible Modular Redundancy™ (FMR): Maximum flexibility during selection of redundancy level – matching the Safety Instrumented Function (SIF)

Technical data



Isolation module

- For electrical isolation of F modules and standard modules (for SIL 3)

Fail-safe digital modules

Digital input module SM 326 F

Digital input module SM 326 F (NAMUR)

Digital output module SM 326 F

Digital output module SM 326 F (PM)

Analog input module SM 336 F

Number of inputs or outputs

up to 24
(1-channel for SIL 2 sensors)
up to 12
(2-channel for SIL 3 sensors)



8 x current sinking/sourcing

6 (15 bit)

Input and output voltage

24 V DC


24 V DC

24 V DC


Diagnostic interrupt

Diagnostic interrupt

Diagnostic interrupt

Diagnostic interrupt

Diagnostic interrupt

output current



2 A per channel at signal "1"

2 A per channel at signal "1"

0/4…20 mA, HART

Order No. group: 6ES7

326-1BK. 1)

326-1RF. 2)

326-2BF. 1)

326-2BF. 1)


1) As SIPLUS component also for extended temperature range -25…+60 °C and corrosive atmosphere/condensation (

2) As SIPLUS component also for corrosive atmosphere/condensation