Specialities |
| Manufacturer | SIEMENS |
| Product title | S5-95F
S5-115F |
| Strength | 1. Inputs with fast response time.
2. Safety-related data communication also possible over communication protocol SINEC-L2 (Profibus-DP).
3. All certifications available according different applications.
4. AK6 or SIL3 or category 4 (EN 954-1) operation is possible.
Definition in the TUV report:
IEC 61508 part1-3 in accordance with SIL1-3.
Safety classes that can be reached...
Operating the S5-95F in quasi-safety mode for AK6 or SIL3 or Cat4. |
| Weakness | 1. I/O modules may only be changed in the deenergized status.
2. Beginning with AK4 SIL2, 2 devices S5 are required (central and extension device), this results in higher extent in work for wiring and a higher price.
3. No availability if one component fails (central, I/O module), no single channel operation.
4. Safety-related parts have to be always in redundant (peripherals, I/O modules), safety-related peripheral only with external wiring.
5. The control of the safety-related outputs requires extent of work for wiring.
6. No diagnostic display exist, error diagnostic via communication module resp. error annunciation module.
7. For the safety-related bus transmission (SINEC-L1), an additional master is necessary (e. g. S5-115U not safety related), with a redundant bus two additional masters are required.
8. No On-line modifications possible.
9. Off-line test intervals for a 2oo2 system is every 3 months (according to IEC 61508).
10. Programming system Step 5 is not a programming system according to IEC 61131-3.
11. Bad support or hotline from SIEMENS. |
| Specialities in prices | 1. Cheaper digital components. |
| Remarks | |
| Manufacturer | SIEMENS |
| Product title | S7-400F/FH |
| Strength | 1. Certification according IEC 61508 up to SIL3.
2. Software redundancy sufficient for SIL3 applications.
3. ProfiSafe driver must be run redundancy for SIL3.
4. Totally integration in the DCS PCS7. Mixed mode with normal S7 systems.
5. Mixed mode single 1oo2 and 2oo2 I/O level is possible.
6. Fieldbus master functionality available. |
| Weakness | 1. VDI/VDE2180 says 'to make strict division between process control protective equipment and process control operation equipment' and 'the hardware must have a modular structure and should be able to be used as an independent individual system'. Then to expensive!
2. I/O modules may only be changed in the deenergized status.
3. The redundant I/O modules are in the same ET200 module board (today).
4. The ET200 must be linked via FO cable (galvanical isolation).
5. Between the central unit and the I/O modules must be a fieldbus with an additional safety layer in the protocol (Profibus-DP with ProfiSafe).
6. Central unit and extension device must be used (ET200 with I/O mod.), this results in higher extent in work for wiring and set up.
7. No availability in 1oo1 CPU and 1oo2 I/O level (SIL3 application). Availability only in 2oo2 CPU and 2oo2 I/O configuration (SIL3).
8. Very complexly programming and configuration of the system. With many safety rules to check.
9. No easy integration.
10. Very high reaction time. Single channel min. 220ms, redundant min. 400ms up to 700ms.
11. Very long compilation time of safety related Step7 programs (bigger projects up to 2h).
12. The control of the safety-related logic requires additional and separate functional logic blocks (limited) in Step7 (prog. Languish). That means extra price.
13. Every hardware units needs separate software license (runtime license).
14. No diagnostic display exist, error diagnostic via ext. HMI or via LED's.
15. No Off-line test in Step7.
16. Bad support or hotline from SIEMENS. System integrator gets no information's about the delivery schedule for components. |
| Specialities in prices | 1. Expensive components (double price for central rack, digital I/O same price and analogue I/O more expensive than HIMA (with independent systems)! |
| Remarks | According to a statement of SIEMENS the development of new (Ex)i I/O safety modules for the S7-400F/FH (ET200) are aspired.
Additional development for digital special version with reaction time min. 100ms. |
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