Siemens 316-2DP / CP343-1 / OPC Communication Issue

PDBeal

Member
Join Date
Feb 2005
Location
South Carolina
Posts
9
Hey,

Have a very strange problem. I have contact the Siemens Hotline, several Siemens App Engineers, KepWare, and anyone else I through could help, but nobody has had any luck figuring out was is going on. Here's the setup:

A 316-2DP with a CP343-1 module. The CP343-1 module has an ip address of 10.0.0.14, and the PC running the OPC server has an ip address of 10.0.0.1. This is a completely isolated network. The 316-2DP also has 2 OP17 attached via the MPI interface, and about 12-15 slave Profibus modules attached through the Profibus interface.

The MPI address are listed as below:
CPU - 2
CP343 - 3
Main OP17 - 5
Remote OP17 - 6

The PC is running KepWare KepServer and is configured to use the Siemens TCP/IP driver. For some strange reason, I loose my OPC communications from my PC to the PLC for no apparent reason, and the only way to regain communication is to STOP the CPU and wait a sec or two, then go back to RUN.

At first I wasn't sure what was going on. I've tried several different things. The CP343-1 card was replaced with a new one. System ran for 2 weeks reading data, then stopped again on Monday Feb 7th, 2005. First though was connection resources. I reconfigured the connection resources to allow 2 PG, 4 OP, and 4 S7 Standard communications which still leaves 2 available connection for the Other communications. (Other communications name pulled from SIMATIC Manager Communications tab of the online Module Information of the CPU 316-2DP. After downloading the new configuration, I was able to establish a connection for 20 minutes of type OP.

Under Kepserver I can configure the type as PC, OP, or PG. According to KepWare I can have 4 connections to a CP343-1 module, 2 of PC, 1 OP, and 1 PG. When I restart the CPU from RUN to STOP to RUN, I can connect and read data over an OP type of connection. However, this only lasts about 20 minutes. I can maintain a connection of PG, but this connection is not stable as every coupld of minutes it will drop off then return.

Has anyone seen this problem before, or have any ideas how this can be resolved? Disconnecting the OP17s make no difference, nor does disconnecting all the Profibus devices and Operator interfaces. WinCC also cannont communicate with the PLC. Siemens Hotline and KepWare are both researching this problem without much luck as of yet.

Any Ideas?
 
Yes, I have seen similar problems with the 443-1, but it's been a few years and it was only with earlier firmware revisions. I am sure Siemens checked this.

I have some ideas, but can you check a couple of things first?

1. When it gets in this state, can you ping it from the command prompt?
2. Does it get into this state completely at random, or does it happen at a certain time of day?
3. Is the Kepware Server only reading from the PLC, or does it write also?
 
To answer your questions.

1. Yes, it can still be pinged when I loose communications. The strangest part is I can still communicate with the PLC through STEP7 over the network after I lose the OPC connection. I have also tried to use the Siemens ISO protocol instead of TCP/IP thinking it could be a TCP/IP issue, but same problem occurs with TCP/IP or ISO protocol.
2. Seems to be completely at random. Sometimes its within 20-30 minutes, other times it took 1-2 weeks.
3. KepWare is only reading. Tags are setup for "Read Only" also.
 
On the surface it doesn't sound like a Siemens issue. Could you try a different OPC Server just to take Kepware out of the equation?
 
If I'm not mistaken , there is a configuration pane in the tcp/ip configurations . Set the timeout upto something like 10 Secs and give it a blast . You can also set fast acknowledge to "on"
 
Well, even if I put KepWare asside, WinCC V5.1SP2 using the Simantic Protocol Suite and TCP/IP I do not get any communications either. However, if I go through the process of ging to run mode STOP, wait a couple of seconds, and back into RUN, then I can get WinCC communications running for a while. Same results that KepWare acheives. The machine does have a licensed copy of the SoftNet S7 software, so I know I'm not hitting a timeout on licenses.

Fred: I set the timeout to 10 seconds, but it doesn't make a difference. I don't see the fast acknowledge on anywhere in KepWare, or in the CP343-1 module.

Honestly to me, because the communications are restored after a transition to STOP and RUN of the CPU, it seems like the Siemens PLC stops responding and never resets anything, untill this transistion from RUN to STOP to RUN.

I have attached the diagnostic buffer from the CP343-1 module, incase it will lead into any other ideas. Unfortunatly, I don't have a time server, so the date and time in the CP343-1 module is incorrect, but I think 01/17/94 will corespond to 02/10/05 in the log file.
 
PDBeal,

The following entry in the diagnostics buffer:
"77 23:22:54:579 17.01.94 Mgt (0x0214/0x00000000)
PG command causes module restart"
Is that caused by you, or does it happen by "it self" ?

Somehow we must know which entries in the diagnostics buffer are relevant to the problems.
Best is an upload of the diagnostics buffer right after the communication has failed.

It doesnt seem to be a software problem as you have tried both WIN CC and KepWare.
Have you tried to alter the communication path. (i.e. exchange cables and/or swithces) ?
Have you checked your ground ?
 
At that given time, that was me telling the CP343-1 card to enter STOP mode and enter RUN mode. This doesn't seem to do anything to the running operations, and I believe it is only pertainant to sending messages between S7 processors, of which I'm not doing.
 
At that given time, that (what ?) was me telling the CP343-1 card to enter STOP mode and enter RUN mode.

I dont grasp what you are trying to say.
Are you saying that it happened by itself ?
Or are you saying that you were doing something with the CP343-1 at the time ? If it is the latter, then we need the diagnostics buffer at the time the problem occured.
 
Sorry had a brain freeze when I wrote that. It should have read

At that given time,I was telling the CP343-1 card to enter STOP mode and enter RUN mode.

I've had a little breakthrough with the Siemens support though. We have been researching the number of connections that can be made to a 316-2DP. We've found some documentation that states two different options. One states 3 MPI connections, 3 DP connections, and then from the Siemens Hotline they state I should have 4 connections, 1 being reserved for programming. I'm currently testing this idea, by disconnecting some of the units on the MPI network, and I'll come back here with any details I find.
 
So what is the final verdict? I am having the exact same problem, the OPC connection just dropped for some reason. All I had to do to the flip the switch on the CP 343-1 to STOP and then to RUN, then the OPC connection re-establishes. Anyone knows how to write codes to put the module to Stop and to Run in the Step 7?
 
Possible conclusion

Hi,

I'd this problem once. You can try incrementing the number of OP links in Harware configuration -> CPU ->communcations. You must indicate the sum of panels and PC that are conecting to the CPU (not only via MPI, also through PROFIBUS or Ethernet).

Sincerely,

Kelkoon
 
Hello Kelkoon,

I cannot find the place to specify the number of PCs connected to the CP module. Can you direct me to it please? Thanks.

Here is my configuration, I have 2 PCs connected to a CP 343-1 through a standard off-the-shelf router. The CP 343-1 is controlled by a S7-315 processor. There are a DI (SM321) and a DO (SM322) module attached as well.

Very simple configuration.

Sincerely,
Alex
 

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