Master Reset, S7-400

I've got a problem with an S7-416 CPU. The last time it was used, the MPI port was defined as a profibus port. Nothing wrong with that. But now, I need to set the port back to MPI, but I can't get the master reset to work properly. What I want to do is set it back to the factory defaults, with the MPI port set to "2".

Here is a snippet from one of the S7-400 manuals. But, it isn't quite clear on steps 5-7 when or if I should release the toggle switch or how long I should expect to wait for each transition. I've tried every combination, and I get the MPI address set to 2, but only with the external fault blinking (should be solid) and no other lights on. As soon as I power off/power on again, it goes back to what it was, so evidently the master reset isn't completing.

If someone has an S7-400 they can test with, it would be great if you could verify the following precedure:

Proceed as follows to reset a CPU to its factory settings:
1. Switch off the mains voltage.
2. If a memory card is inserted in the CPU, always remove the memory card.
3. Hold the toggle switch in the MRES setting and switch the mains voltage on again.
4. Wait until LED pattern 1 from the following overview is displayed.
5. Release the toggle switch, set it back to MRES within 3 seconds and hold it in this
position.
After approx. 4 seconds all the LEDs light up.
6. Wait until LED pattern 2 from the following overview is displayed.
This LED pattern lights up for approximately 5 seconds. During this period you can abort
the resetting procedure by releasing the toggle switch.
7. Wait until LED pattern 3 from the following overview is displayed, and release the toggle
switch again.
The CPU is now reset to its factory settings. It starts without buffering and goes to STOP
mode. The event "Reset to factory setting" is entered in the diagnostic buffer.

Here is the pic that displays the expected patterns.

Try it with this sequence:

Operating Sequence for Memory Reset
Case A: You want to download a complete, new user program to the CPU.
1. Turn the switch to the STOP position.
Result: The STOP LED lights up.
2. Turn the switch to the MRES setting and keep it at this setting.
Result: The STOP LED is dark for a second, light for a second, dark for a
second and then remains on.
3. Turn the switch back to the STOP setting, then to the MRES setting again
within the next 3 seconds and back to STOP.
Result: The STOP LED flashes for at least 3 seconds at 2 Hz (memory reset is
executed) and then lights up permanently


This should also reset the hardware config.
Don't forget to remove the memory card and the battery.



Source (page 1-16):

http://support.automation.siemens.com/WW/llisapi.dll?query=6es7416&func=cslib.cssearch&content=skm%2Fmain.asp〈=en&siteid=cseus&objaction=cssearch&searchinprim=&nodeid99=&x=0&y=0

That doesn't work. It resets everything except for the MPI address. There is a note in the manual that MPI parameters are retained after a normal memory reset, which is why they have the special memory reset above to set the default values. But, it doesn't work for me.

Can't you go online with Profibus and download a new hardware config?

I didn't have a profibus adapter last night, so I couldn't try. I'll bring one home tonight and give it a try.

It's kind of strange that I can't do an overall reset though and revert it back to MPI. I was hoping someone had a test bench where they could try it out.

go to the hardwaer setting goto plc object properties goto general and network the mpi.

That option isn't available in the general tab of an S7-400. Anyway, I've already set the MPI/DP port to MPI and gave it an address of 2, but that doesn't matter since I wouldn't be able to connect to it anyway because the MPI port is actually a DP. I need to reset the factory settings with their procedure, since a normal master reset doesn't reset the MPI address.

I had another S7-400 delivered today, and I'll use that one to burn a memory card with a new hardware config in it, and then put that one in the other CPU and see if I can connect to it then.

I still don't understand why the master reset as described above doesn't work. I'll get with the local Siemens rep next week and see if he can figure it out.

uhave only one port in plc??mpi/dp...

go to Accessible Nodes an try to reset the plc.

When you reset a S7 cpu, my understanding is that the com ports do not reset to "factory defaults".

S7Guy said:

I didn't have a profibus adapter last night, so I couldn't try. I'll bring one home tonight and give it a try.

It's kind of strange that I can't do an overall reset though and revert it back to MPI. I was hoping someone had a test bench where they could try it out.

Click to expand...

Take that Profibus adapter home.
Open project, open CPU till Blocks folder.
Use adapter and Accessible Nodes to connect to the CPU, transfer SDB from offline to online.
And you're done, HW-config is downloaded, or at least you should now be able to connect using the MPI adapter.

Mike_RH said:

When you reset a S7 cpu, my understanding is that the com ports do not reset to "factory defaults".

Click to expand...

They do when you use the sequence above, and Siemens explicitly states it in their documentation. But when I do exactly as described, I only get as far as a blinking red ext fault light, and in their chart they say it should go solid. I'm guessing that this is why the master reset doesn't complete, and goes back to the former settings on startup.

Jeebs said:

Take that Profibus adapter home.
Open project, open CPU till Blocks folder.
Use adapter and Accessible Nodes to connect to the CPU, transfer SDB from offline to online.
And you're done, HW-config is downloaded, or at least you should now be able to connect using the MPI adapter.

Click to expand...

I'm going to try it again tonight Jeebs. Thanks.

S7 Guy, I have to disagree, the manual "Programming with S7" chapter 19:

When a memory reset is performed on an S7 CPU, the following happens:​

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The contents of the diagnostic buffer and the MPI parameters are retained.

My expereince in resetting a CPU is that the MPI port retains its configuration (baud rate and node number), if the port is a configurable port (MPI/DP), then it retains its settings (baud rate, network and node number).

Mike

Thats when you use the Clear/Reset command from Simatic Manager. I'm not sure it's the same kind of reset as the Master Reset, maybe we should try it. Then we'd know.

Anycase, as to why the reset hangs is a mystery to me. We have had it happen once or twice I think, redownloaded the HW-Config and both are still running.