Entry type: FAQ, Entry ID: 14198063, Entry date: 08/09/2010

How can you combine fail-safe and standard modules in the ET 200 stations?

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  • Associated product(s)

The following security classes are based on the associated standards:

  • for SIL on IEC 62061 / IEC 61511
  • for PL on ISO 13849-1:2006
  • for category on EN 954-1:1997

Combination of standard and fail-safe modules with ET 200S
If you use the standard output module of the type DC24V/0.5A in combination with power module PM-E F for safe switch-off, you can attain SIL 2PL d/category 3. The standard output modules you can use are given in Entry ID: 39198632.

If you want to have safe switch-off done via a fail-safe output module (F-DO), you can combine standard and fail-safe input/output modules and attain SIL 3/PL e/category 4. However, make sure that you use an appropriate power module PM-E (e.g. 6ES7138-4CB11-0AB0). The SIMATIC Selection Tool (see Entry ID: 26484854) supports you in this.

Combination of standard and fail-safe modules with ET 200M
Refer to the manual "Fail-safe signal modules" (Entry ID 19026151, section 2.3 Configuration with F-SMs in safety mode).
You can also use a combination of fail-safe and standard input/output blocks in an ET 200M station. To attain safety class SIL 3/PL e/category 4 with combined operation in the ET 200M station, you need the isolation module if you are using the following modules of the ET 200M or their predecessor versions.

Module Order number
SM326, 24DI, fail-safe 6ES7326-1BK01-0AB0
SM326, 8DI, NAMUR, fail-safe 6ES7326-1RF00-0AB0
SM336, 6AI, fail-safe 6ES7336-1HE00-0AB0
SM326, 10DO, fail-safe 6ES7326-2BF01-0AB0
SM326, 8DO, fail-safe 6ES7326-2BF40-0AB0

The isolation module separates the potential groups of the fail-safe and standard modules. In this case, the standard I/O modules must be slotted to the left and the fail-safe modules to the right of the isolation module.

The isolation module must also be used for the above-mentioned modules in SIL3/Cat.4/PLe applications as follows:

  • Generally if the F-SMs are used centrally in an S7-300.
  • Generally if the PROFIBUS DP is set up with copper cable.
  • If the PROFIBUS DP is set up with fiber optic cable with IM 153-2FO and you require combined operation of standard and the above-mentioned F-SMs in an ET 200M.

The following successor modules can be implemented without isolator module up to SIL3/Cat.4/PLe:

Module Order number
SM326, 24DI, fail-safe 6ES7326-1BK02-0AB0
SM336, 6AI, HART, fail-safe 6ES7336-4GE00-0AB0
SM326, 10DO, fail-safe 6ES7326-2BF10-0AB0
SM326, 8DO, fail-safe 6ES7326-2BF41-0AB0

Safety Integrated, Mixed operation, PROFIsafe, Distributed Safety mixed operation, Fail-safe, Isolation module, Power module, ET 200 family, DI, DQ, Configuration editor