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What I have to do when one PLC of my redundancy system fail?

Created by: LongLe at: 12/30/2019 8:45 AM (2 Replies)

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12/30/2019 8:45 AM	Rate (0)
LongLe Advanced Member Joined: 10/8/2018 Last visit: 11/5/2024 Posts: 6 Rating: (0)	I'm new to S7-400H redundancy systems. My plant have a redundancy systems S7-400. I know when the master PLC fail, the slave PLC is working to keep the process doesn't shutdown. As the topic, I want to know what I have to do when one PLC of my redundancy system fail? I already have a spare- part PLC s7-400H and memory card of the master PLC. But i don't know how to configure the new PLC, how to upload old software and donwload it to new Master PLC. How i know my slave PLC will work fine when the master PLC fail and how to replace that PLC? Thanks all so much.

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12/30/2019 12:15 PM	Rate (0)
legacy support Silver Member Joined: 7/15/2008 Last visit: 10/6/2024 Posts: 382 Rating: (44)	LongLe I'm new to S7-400H redundancy systems. My plant have a redundancy systems S7-400. I know when the master PLC fail, the slave PLC is working to keep the process doesn't shutdown. As the topic, I want to know what I have to do when one PLC of my redundancy system fail? I already have a spare- part PLC s7-400H and memory card of the master PLC. But i don't know how to configure the new PLC, how to upload old software and donwload it to new Master PLC. How i know my slave PLC will work fine when the master PLC fail and how to replace that PLC? Thanks all so much. Hello LongLe There are different failure modes, that may require different actions. I have over 15 S7-400H Systems, and in the last 10 Years and did not have to replace anything, except the batteries. In regards to the failure modes. The most common one that I encountered was the failure of the Y-Fiber link between the 2 PLC's. (2 lite green lights above the fiber link module). Usually I just need to reinsert the link cables to make sure they are seated properly. After the Link Lights on both PLC modules are OK , it is just a matter of switching the Slave PLC back on, and they will synchronize automatically again. If not... turn off power supply to Slave CPU... remove Batteries... wait 1 minute....reinstall Batteries. Ensure the PLC Switch of the Slave CPU is in Stop Mode...then turn your power supply back on. The Slave CPU will now through a startup.. the stop light will flash.. for 10min...yes 10min.. go have a coffee or a tea... after 10min the stop light will stop flashing and stay solid.. now place the mode switch of your PLC to Run... the Slave PLC should now synchronize with the master PLC and go to Run... If for any reason you wish to replace the PLC with a new PLC, follow the same procedure, but ensure that the switch on the side of the PLC indicates the correct rack number... Usually the Left PLC is rack 0 and the Right PLC is rack 1 . But you can open your offline HW config and check. So with this said, if your Master PLC is still running and OK, you do not need any PC/PG to replace a S7-400H PLC.. The S7-400H System was build and designed with this in mind..and there are also Manuals available to get familiar with these systems.. Regards / m.f.g

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This contribution was helpful to 3 thankful Users SOble dchartier Ajiajesh

12/30/2019 1:01 PM	Rate (0)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 11/16/2024 Posts: 12294 Rating: (2691)	Hello LongLe; Not only (as suggested by Legacy Support) must you be very sure that the failed S7-400H master CPU needs replacement, but the requirements for a replacement CPU are precise: you need a CPU of the same hardware and firmware version as the original (and the standby CPU that is now operating as a stand-alone PLC), and a similar memory card for both CPUs. Since the best information source for Siemens PLCs is always the System manual, look at the screnshot below, detailing the minimal conditions and procedure to replace a CPU in a S7-400H sytem: SIMATIC Fault-tolerant systems S7-400H (V6.0) https://support.industry.siemens.com/cs/us/en/view/82478488 Hope this helps, Daniel Chartier Attachment S7-400H replacing a CPU.jpg (453 Downloads)

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