WinCC,Profibus Communication Problem

hi all,
I am a beginner in WinCC and siemens PLCs.I need to sort out some problems in one of our WinCC project.So I kindly request some expert help to solve the following Issues.

System:

There are two redundant WinCC servers connected to four S5 PLCs via an Ethernet switch(each one of them connected to each RJ45 port of the ESM).To one of the port of the ESM an Ethernet Link Module is connected which interfaces the above system with an existing SINEC H1 bus.The WinCC servers are also connected to a Profibus network of seven C7 PLCs.

A Network layout is attached.

Software:-
OS :WinXP Prof, WinCC 6.0

Hardware:-
CP cards:-CP 535( in S5 PLcs)
CP 1613( in PC for Ehternet)
CP 5613(for Profibus N/W)

Problem:-

1. There is around 5 sec delay in WinCC - PLC Communication.The acceptable delay is below 2 sec.
2. With both the PCs connected to the Profibus N/W, there occurs some communication loss.But If I remove one of the PCs from the Profibus N/W,communication is OK.The problem is worse when both the servers are connected and opened on the same page.


Thanks in advance,

CLP

need some suggestions

hi,
anything wrong in the way i explained the problem???no one seems to be interested.......

Any suggestions....???
1. why there is too much delay in SCADA(WinCC) to PLC(S5 PLC) communication?

2. There is some communication loss when both redundant servers are connected to a profibus network of seven C7 PLCs.If one of the server is removed from the profibus network, it is OK. The situation becomes worse when both the servers are connected and opened on the same page.


Thanks to all the views

bye,

CLP

How are you measuring the updates?

What are the tag triggers (updates) set at?

Hello CLP!

I think the reason for your slow communication is the two servers itself...
When only one server is connected the traffic is probably already high (based on the fact that you have 1028 tags licences), meaning the amount of data that needs to be transmitted on the profibus is already pushing the bandwidth limit.
When you connect the second server the bandwidth of the profibus is pushed beyond its limits due to the fact that both servers are trying to talk to the same plc at the same time, probably giving you a "slowdown" in communication rate. I don't think the S5 plc's are very good at communicating to multiple partners at the same time (slow cpu).

A possible solution to this would be to increase the profibus speed.
Is the speed set to 1,5 now? It can go all the way up to 12.

It is also possible that the wincc servers are trying to reach the plc's over both the Ethernet and the profibus connections, this can also cause extra traffic / collisions in data transfers.

In general it sounds like a profibus bandwidth problem.

Hope this helps a little...

Regards
Borte

hi Borte,
Thankyou for your suggestion.

As if now, the communication rate is set to 500Kbps.

cheers,
CLP

500kbps sounds slow for the communication rate.
Normal speed for a profibus network is 1,5Mbps.
If possible try to increase the speed, should help a lot on your problem.

Cheers
Borte

borte,
Thankyou for your help.

As you can see from the above figure, We have two N/Ws connected to WInCC servers.

1. Ethernet N/W connecting to the S5 PLCs.

Problem here:- The WinCC to PLC communication is slow.

2. Profibus N/W connecting seven C7 PLCs.

Problem here:- Communication loss occurs when both the redundant servers are connected to the Profibus N/W.With just one server connected ,it is OK.

To solve this we have put the Communication speed to min,ie., 500Kbps.(bcoz of too much load on the Bandwidth.)

I have just found a link which I think will be useful.

http://www.plctalk.net/qanda/showthread.php?threadid=7728&highlight=wincc

Another problem I am facing is Customer doesn't want me to play around much with his system.(bcoz he came to know that i'm a fresher)
banghead

Thank you once again,
CLP

The following ideas came to my mind after reading your last post CLP...

1. Ethernet N/W connecting to the S5 PLCs.

Problem here:- The WinCC to PLC communication is slow.

Click to expand...

If the communication is always slow, then it can be caused by network bandwidth limits caused by other traffic on this network, plc communication tends to send a lot of small network packets causing a lot of traffic on the network. So it should always be a dedicated network for process communication (and not being used for anything else).
It can also be caused by improper network configuration so that some of the communication peers on the network are trying to reach an unreachable or unexsisting target.
Is this communication slow even when the new server is disconnected?

2. Profibus N/W connecting seven C7 PLCs.

Problem here:- Communication loss occurs when both the redundant servers are connected to the Profibus N/W.With just one server connected ,it is OK.

To solve this we have put the Communication speed to min,ie., 500Kbps.(bcoz of too much load on the Bandwidth.)

Click to expand...

This actually sound like cable problems / electrical noise, since the communication loss can be solved by reducing the speed of the network. I have earlier had problems with noise on a pb network, the shielding and ground of the different units are important when problems like this occurs. Have a look at the ground / shielding of the cable / units. This could help getting the speed back up to a normal level.

Tell your customer that things like noise and grounding can be checked without risking any downtime on the equipment. This can still be done while it is "in production". Hope this helps for the "playing around" part...

Regards
Borte

Borte,
Thankyou for your interest.

To make the picture complete..... I am attaching a picture of full system.

As shown we have 3 identical Systems(1,2,3) connected to the same H1 bus.Only in the system2,we have a profibus network of 7 C7 PLC.This System2 figure was attached to my first post.

Problems:
1. The WinCC-PLC commn delay exist in all the systems.
2. In system 2, the commn loss in profibus N/W.(occurs only when both the redundant PCs connected simultaneously)

Is this communication slow even when the new server is disconnected?

Click to expand...

In any of the above system,If one of the redundant partner is removed, delay decreases by half. (but still 2 sec)

PLC cycle time = around 34 msec
PC = P4,1 GB Ram,WinXp Prof
WinCC= Ver 6.0

What we tried...

1.If we isolate system 1 from the remaining,still the problem exists.
2. If we connect the PLC directly to WinCC servers bypassing the ESM,ELM still the problem exist( Delay with 1 server=2 sec, 2 server= 4sec approx)

So it should always be a dedicated network for process communication

Click to expand...

I have a doubt:-
In the picture below,Suppose I want to dedicate a small N/W for each system(ie., 4 S5 PLCs and 2 PCs with out increasing the traffic in the H1 bus) but still want all the three Systems to be interconnected in some way so as to monitor any PLC from any where, How it should be connected??

For Problem2, I have to go and check the grounding and shielding,as you told.

Thank you for your time and help
CLP

Repeted Msg removed

Repeted Msg removed

Hello again CLP!

Sorry for the late response but I had to reinstall my computer last week.

The problem cannot be caused by the network configuration since you still have the problem after isolating the system...

I'm starting to run out of options on your communication delay...

A 2-second delay when one server is connected seems normal.

We are also using a wincc server (5.2) to communicate to 50 different plc's, over both pb and Ethernet. We are using a 2 second heartbeat pulse from each plc and the server has no problem reading this pulse. We are also using a development station that sometimes is running (always connected), this is causing a small increase in the delay to only one of the plc's but nothing big.
I think the reason for this delay is the pb speed since this plc's is connected to that network. All the other plc's (specially the one's connected to the Ethernet) are running fine even when both servers are connected.

I'll se if I can get a co-worker to have a look at the server config.


Regards
Borte