Siemens S-7 SF LED Status
- Thread starter kupeyy
- Start date
Ned_Flanders
Member
If it is an existing installation, it sounds like it cannot find the remote i/o. Can you interrogate the cpu?
I have seen this on German machinery, where emergency stopping the machine will cause the led to light - I think because it causes the 24v to drop out.
I have seen this on German machinery, where emergency stopping the machine will cause the led to light - I think because it causes the 24v to drop out.
Ned_Flanders
Member
It could also be something within the program - like addressing a datablock or data word that isn't there! Loose i/o cards? Disconnected link cabe on an expansion rack?
What is it?
Well, according to Siemens very own manual available free-of-charge from the very own website, it's a general purpose catch-all System Fault indicator and can be either hardware or software related. One thing's for sure - your controller is not working when that's on. It is not a specific error indicator. Treat it as you would a cloud of smoke above a control cabinet. You now need to find out what caused the SF LED to come on.
Use the Diagnostics Buffer in the PLC. Although I suspect giving that advice to someone who hasn't mastered the SF LED is going to produce more questions.
Well, according to Siemens very own manual available free-of-charge from the very own website, it's a general purpose catch-all System Fault indicator and can be either hardware or software related. One thing's for sure - your controller is not working when that's on. It is not a specific error indicator. Treat it as you would a cloud of smoke above a control cabinet. You now need to find out what caused the SF LED to come on.
Use the Diagnostics Buffer in the PLC. Although I suspect giving that advice to someone who hasn't mastered the SF LED is going to produce more questions.
L D[AR2P#0.0]
Lifetime Supporting Member
Note that if empty error OB's have been programmed then the CPU will stay in run even with the SF light on.
ivo.maenen
Member
- Join Date
- Nov 2003
- Posts
- 663
uptown47
Lifetime Supporting Member
As has been mentioned you need to interrogate your diagnostic buffer (PLC - Diagnostics - Module Information - I think..).
There are several OB's that you can utilise to stop your PLC from going into STOP mode. OB121 / OB122 (software / hardware problems for instance).
Remember that if the PLC is in STOP then, even if you correct the fault, you need to switch to STOP and then back to RUN on the front of the PLC to start it again
Good luck!
There are several OB's that you can utilise to stop your PLC from going into STOP mode. OB121 / OB122 (software / hardware problems for instance).
Remember that if the PLC is in STOP then, even if you correct the fault, you need to switch to STOP and then back to RUN on the front of the PLC to start it again
Good luck!
sakthi2086
Member
if AI and AO module is showing indication red in SF what is the cause while ET200M is communicating
kidemaster
Member
Hi guys,
I have the same problem with random SF LED on CPU 315 2 DP. System worked flawlessly for 10 years and now starts to fail. We have checked power supply (replace with new one), replace all DO cards, replace IM365, replace CPU and the problem won't let go. If someone have an idea, we are here to listen. Thank you in advance.
I have the same problem with random SF LED on CPU 315 2 DP. System worked flawlessly for 10 years and now starts to fail. We have checked power supply (replace with new one), replace all DO cards, replace IM365, replace CPU and the problem won't let go. If someone have an idea, we are here to listen. Thank you in advance.
kidemaster,
You might get a better response if you create a new thread. When you do, you'll probably need to include more details about your system, like what IO is being used, and an archive of the PLC project. An export of the diagnostic buffer is very important info, but we probably need more than that.
maxketcham
Lifetime Supporting Member
I seriously have to ask, why is this showing up as a new post today on the board? It clearly hasn't been active since 2013 and it was like 3rd on my list of posts today.
sigmadelta
Member
I had a very weird problem like this with an S7-300 as well. It turned out to be a DI card that caused a problem in the backplane. The way I resolved the problem was to have a new module of each type on-hand, and to replace the first one in the backplane. If the problem didn't go away, then I put the first module back, and replaced the second one in the backplane... etc. until the problem disappeared for good. The DI module was interrupting the modules to the right intermittently.
uptown47
Lifetime Supporting Member
This seems like it's an issue with something the CPU is connected to peripherally? If you put OB122 into your code and download that will at least stop the CPU going into 'STOP' mode to give you time to try and diagnose the problem.
kidemaster
Member
Here is the HW-Config picture.
After replacing almost everything from UR(1) I still have the same problem. Sometimes system works for 2 hours and then go to SF few times in 10 minutes. There is no unique pattern.
After replacing almost everything from UR(1) I still have the same problem. Sometimes system works for 2 hours and then go to SF few times in 10 minutes. There is no unique pattern.
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