S7 - 300 Problem

captain_is · Feb 16, 2011

Hi guys,

I have a problem with an S7-300 plc.

To describe a little the problem. This plc controls 2 VSD's. When is a power loss and then the power goes back my PLC doesn't start running until i go there and reset it. I know that normally the PLC will reload it's configuration and start running the program again if there is a power loss.

Does anyone had this problem before? I need to make a setting or something?
I thought to put an UPS for the plc?But i wonder if it is another solution maybe from configuration or something that i miss.

Thanks in advance guys, You are the best!

L D[AR2P#0.0] · Feb 16, 2011

Leave the plc in stop and use the module diagnostics to interrogate the diagnostic buffer - this will indicate why the plc will not go into run or why it has stopped.

captain_is · Feb 16, 2011

L D[AR2 said:
Leave the plc in stop and use the module diagnostics to interrogate the diagnostic buffer - this will indicate why the plc will not go into run or why it has stopped.

I understand, the problem is that i am not right now near the plc..I will try to do that to see what is the problem.

Are there specific issues that can generate this type of failure?I'm not very experienced with Siemens plc's.

Thanks for your reply.

uptown47 · Feb 16, 2011

It should go back into Run mode if the power is lost and then regained. Is there perhaps some software in OB100 or one of the 'restart' OB's that is not being run unless the switch is cycled to 'Stop' and then back to 'Run' that perhaps is causing the PLC to go into Stop ??

Do you have OB100 / OB101 etc in your software??

;-)

Paul B · Feb 18, 2011

LD is pointing you to using the diagnostics to determine which error OB's your program needs to handle. Since you are not familiar with Siemens I will tell you that when a fault occurs the S7 will call an error OB like OB86, etc. If the block does not exist the plc will go into stop mode. Your steps to counter this will consist of adding the appropriate OB and using code to fix the fault. You can cheat by just loading the appropriate OB, but a proper way is to use code in that OB as needed to handle the fault in a way that safely controls the system. Hope this helps.

msbala.alh2 · Mar 2, 2011

please help me in s7 300

i have s7 300 plc cpu 312
in this i need to connect a 7 segment display where it should indicate 3 digits output.
how to interconnect from cpu
what is 7 segment display
any siemens make 7 segment display ia available

msbala

Longhorn · Mar 2, 2011

msbala.alh2 said:
i have s7 300 plc cpu 312
in this i need to connect a 7 segment display where it should indicate 3 digits output.
how to interconnect from cpu
what is 7 segment display
any siemens make 7 segment display ia available

msbala

I suggest you start a new thread / topic as this thread is regarding something completely different, that way you stand a better chance of recieving a positive response.

msbala.alh2 · Mar 2, 2011

Help

How to start new thread

msbala

uptown47 · Mar 3, 2011

Just go here:
http://www.plctalk.net/qanda/forumdisplay.php?f=2

And choose "Start new thread" which is just below the Google search bar but over on the left of the page. (just above the start of the forums).

HTH

sinaralf · Mar 28, 2011

S7-300 (sf & bf)

Hi Guys,

We are having s system where the CPU (CPU315-2DP)is link up with the DP PROFIBUS to the dc drives (18units), interface module (IM153-1AA03-OXBO), and the OP.
For some reasons the current status as follows -
1) CPU315
- SF Led ON
- BF Led Flashing
2) IM153-1
- BF Led ON

We have carried out the diagnostic, but could not find the root cause of the error indication. We noticed that all the units are mismtached with the CPU. Attached the result from the diagoses for your reference. Please comment on how we could identify the bus error or other errors.

Thank you,

Sinaralf

KalleOlsen · Mar 28, 2011

You have presumably tripplechecked the wiring?
And read the guidelines here: http://www.profibus.com/downloads/
And searched for 'Profibus' in this forum?

K

sinaralf · Mar 28, 2011

Dear K,

Thank you.

Most probably from the cable,termination right?
I will check again

Sinaralf

KalleOlsen · Mar 28, 2011

Whenever you connect ONLY ONE cable to a profiplug, use the connection CLOSEST TO YOUR NOSE! And put the terminal switch -> ON.

Kalle

S7 - 300 Problem

captain_is

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L D[AR2P#0.0]

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captain_is

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uptown47

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Paul B

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msbala.alh2

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Longhorn

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msbala.alh2

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uptown47

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sinaralf

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KalleOlsen

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sinaralf

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KalleOlsen

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