Problem with Profibus

Hello
I need some help.
I have a beverage filler that works with CPU 414-3 and remote ET 200L and ET200M and the network is a profibus.
I have a random problem with the following message:
On remote - Bus Fault and System Fault
On CPU - Bus Fault and external Fault
If I turn the system off and on again works fine until the problem shows again.
Thanks

Hello Carlos;

First plae I would look is in the diagnostic buffers of the CPU and the slaves. The system will accumulate information on all the latest events (on the CPU, the diagnostic buffer can be setup to hold up to 100 events, which can be useful to understand the source of intermittent problems). Especially try to find out if only one of the slaves is involved in the bus fault, or if all of them give the same timestamp for the loss of comms. You can post the error messages here if you have trouble understanding them (note that for one bus fault you may have 2 or more messages, so don't limit yourself to the first one).
One thing you could look at is the Profibus connectors on your slaves. I have seen the case where a less-than-perfect connection of the shield inside the connector will cause a break of communication in machines subjected to steady or strong vibrations. As they were intermittent (and connection seemed fine when we checked in a shutdown) they were hard to diagnose. Worst case, rewire them properly to ensure adequsate connection of wires and shield. If perchance you are not using Sioe,mens or Belden profibus-DP cables, the jacket diameter might not be exactly adjusted to the connectors, and allow the shield to slip out of the housing connector.
Don't hesitate to come back to us with any other information and questions.
Hope this helps,
Daniel Chartier

hello Daniel
Thanks for your help I am going to teste your information.
The error I have is: I/O access error when updating the process image input.
See if you can help, I am about ready to replace the input card
Carlos

Hello Carlos.

As the problem is intermittent, then the most probable cause is a cabling problem. Another cause could be that one of the ET200's have a defective Profibus module.

You can do two things:

1. Add error OBs to avoid the PLC from going to STOP mode when there is a fault on the Profibus network.
I typically have OB80, OB81, OB82, OB85 and OB86 configured (Not all CPUs support all OBs).
Notice: There may be cases where you do NOT want to add the error OBs. If you want the CPU to STOP when there is one of the problems that the error OBs cover, then do not add them.

2. Carefully check all Profibus cables and all connectors. Look for cables that have been damaged.

I have now the same problem.I am using 315-2dp and et200m(IM153).And all of them have the same led status and giving sf and flashing bf.Diagnostic buffer is giving the following error:

Event 1 of 100: Event ID 16# 5371
​

Distributed I/Os: end of the synchronization with a DP master
​

Slot of the DP master: 2
​

Number of distributed stations: 0
​

Incoming event
​

03:34:44:015 pm 10/30/06​

​

I am looking forward to your help.Thank you.​

Hello Hans Andersen.

Not sure that it is the same problem.
That diagnostic buffer entry is only about startup of the Profibus network. The diagnostic buffer entry that you are looking for is probably not the very last one in the buffer.

JesperMP said:

Hello Hans Andersen.

Not sure that it is the same problem.
That diagnostic buffer entry is only about startup of the Profibus network. The diagnostic buffer entry that you are looking for is probably not the very last one in the buffer.

Click to expand...

I have still problem with profibus.Address of CPU is 1.Address of IM153-1 is 2.I am using 6es7 972-0bb50-0xa0 as bus connector for both module.And I am attaching Hardware diacnostics for dp slave.Is my problem the profibus cable or configuration.

Is using of RS 485 repeater a must.I am not using it.

HansAndersen said:

Is using of RS 485 repeater a must.I am not using it.

Click to expand...

It all depends on your cable lenghts, number of slaves and the bus speed. Could you give us a bit more information about the network you have built? How many masters and slaves did you use, what is the distance between the devices and what is the configured bus speed?


You can also check the termination resistors. The switch at the start and end of your network should be in the on position, the others in the off position.

There is one master and one slave node.They are communicating with each others by 187.5 bauds.Distance between modules is just 1 meter.Thermination resistors are all on.

HansAndersen said:

There is one master and one slave node.They are communicating with each others by 187.5 bauds.Distance between modules is just 1 meter.Thermination resistors are all on.

Click to expand...

You do not need a repeater for this situation. But I would recommend to use a minimum cable length of 2 meter when you only have 2 devices.

There are some other things you can check:

-Is the electrical connection correct (A and B (red) lines the same colour on both connectors, both cables connected to the “IN-side” of the connector)

-Does the configuration of the IM153 match the one you configured in the HW configuration

-Did you switch off the power of the IM153 after changing the Profibus address?

Jobbe said:

You do not need a repeater for this situation. But I would recommend to use a minimum cable length of 2 meter when you only have 2 devices.

There are some other things you can check:

-Is the electrical connection correct (A and B (red) lines the same colour on both connectors, both cables connected to the “IN-side” of the connector)

-Does the configuration of the IM153 match the one you configured in the HW configuration

-Did you switch off the power of the IM153 after changing the Profibus address?

Click to expand...

Ok.I'll try your suggest about cable lenght of 2 meters tomorrow.I have checked electrical connections with cable colours and tried switch off and then on lots of time and they are all surely ok.My cpu is not seeing IM153 as real.I think Configuration is ok.

Did this system ever work ?
Carlos has a system were the error is intermittent, but for you it sounds like it has never been working.

If you have a CP5511 or CP5611, you can try to go online with the diagnostics in the "Set PG/PC interface" utility.
You should be able to see the passive DP node #2 as well as the master nodes #1 and the PC (typically #0). In that way you can check if the slave is present on the network.
If not remove the purple profibus cable and connect the grey "drop-cable" directly from the CP5511/CP5611. If the slave appears, you know that the problem lies with the cable or the connectors.

Just a piece of general advice for anyone who is requested to check the Diagnostic Buffer in S7-300/400.

DON'T post just one entry here by typing it in. Very often there is no value in seeing a single diagnotic buffer entry. To make a sensible analysis people need to see the sequence of events leading to a problem. STEP7 has the facility to save the diagnostic buffer to disk. If you're not confident about using the Diagnostic Buffer yourself, then save it and post the plain text file here for others to read.

Ken

JesperMP said:

Did this system ever work ?
Carlos has a system were the error is intermittent, but for you it sounds like it has never been working.

If you have a CP5511 or CP5611, you can try to go online with the diagnostics in the "Set PG/PC interface" utility.
You should be able to see the passive DP node #2 as well as the master nodes #1 and the PC (typically #0). In that way you can check if the slave is present on the network.
If not remove the purple profibus cable and connect the grey "drop-cable" directly from the CP5511/CP5611. If the slave appears, you know that the problem lies with the cable or the connectors.

Click to expand...

Yes everything is as you have mentioned.I am using CP5511.I attached Simatic net diagnostic.I am installing a new system that will control Boiler unit in our mill.Both of modules (cpu and et200m) have SF led and flashing bf led.I realy need help.