WinCC Flex Communication trouble

edda

Member
edda
Join Date
Jun 2008
Location
At the office
Posts
100
Hi!

I have a little problem with some ethernet communiation in WinCC Flexible , I have never worked with WinCC Flexible before so I would need some help.

A new customer to me has a little system that includes the following:

- 314C-2DP CPU
- One IM152 Node
- Two PM-E Nodes
- Two MP277 OP-Panles via Profibus
- One MP370 via Ethernet
- One MP377 via Ethernet

The trouble is that the two panels that communicates via Ethernet (MP370/MP377) responds real slow. Sometimes they just stop updating but sometimes they work as they should.

For example.
Let’s say that I open a valve manually, when it’s open the control byte (each value has a byte that indicates the status of the valve) is ONE and it indicates green as it should. From the Valve is fully until the panel indicates is 1-2seconds (give or take) and that’s OK.

But if I go online in Monitor / Modify and modify something the communication to the panel suddenly goes mad and if I do the same it takes about 20-30 seconds until the valve indicates open in the OP-Panel.

From the beginning the MP370 and MP377 were over Profibus but they tried changed it to Ethernet but it was the same. I never use the Simens panels normally so I don’t know where to start looking.

One strange thing, in the CPU under communication (online) there it shows:
PG Communications = 1
OP Communications = 2
Other Communications = 1

They OP Communications is the two M277 via Profibus (they work as they should) and the PG is me. But the other two panels via Ethernet is only one and under other communications?!

They have tried changing the communication resources to 4/4/4 (PG/OP/S7 Basic) but also to other settings…

I have not been with them until now, so I don’t know exactly what they have tried or done them self…

Here is a link to download the S7 project

http://www.aitech.se/SAH_101011.zip

Best Regards :unsure:

Edmund
 
Hej Edmund.

The problem is not related to reserved communication connections. If there are no connections available, the communication will fail, not just slow down.

How are the two MP370/MP377 panels connected to the 314C-2DP CPU ?
Via a CP343-1 ?
Or maybe a NetLink (or similar) connected to the X1 port on the CPU ?
Or maybe a NetLink (or similar) connected to the X2 port on the CPU ?

Anyway, if connected via CP343-1 or X1, the MPI bus is overloaded.
Or if connected via X2, the DP bus is overloaded.
Or there are simply too much communication load for this small CPU.

I am pretty sure that the remedy will be to decrease the communication load, or the upgrade the CPU to one with higher performance and an integral ethernet port.
The bad news is that the 314C-2DP doesnt have a direct replacement.
I really really hate the socalled "compact" CPUs. To fix this will take some more effort than would have been necessary with a normal CPU.
 
JesperMP said:
Hej Edmund.

The problem is not related to reserved communication connections. If there are no connections available, the communication will fail, not just slow down.

How are the two MP370/MP377 panels connected to the 314C-2DP CPU ?
Via a CP343-1 ?
Or maybe a NetLink (or similar) connected to the X1 port on the CPU ?
Or maybe a NetLink (or similar) connected to the X2 port on the CPU ?

Anyway, if connected via CP343-1 or X1, the MPI bus is overloaded.
Or if connected via X2, the DP bus is overloaded.
Or there are simply too much communication load for this small CPU.

I am pretty sure that the remedy will be to decrease the communication load, or the upgrade the CPU to one with higher performance and an integral ethernet port.
The bad news is that the 314C-2DP doesnt have a direct replacement.
I really really hate the socalled "compact" CPUs. To fix this will take some more effort than would have been necessary with a normal CPU.
Click to expand...

Hi Jesper!

Thanks for your quick reply.

The two paneles (MP370/MP377) are connected to a CP343-1 (1EX11-0XE0) that are located last in the Main Rack.

From the Ethernet port on the CP343-1 the cable goes to a Phoenix Switch and from there to each panel. When I look at the leds on the switch the connection seam real slow (very little activity)...

I checked the CPU load (but only when the machine was off) and it was ok, maybe 40% on both work memory and load memory. The CycleTime was also pretty normal.

But let’s say that the MPI bus are overloaded now, but that don’t explain why they had this problem also when they had the communication over Profibus? But I´m not sure if they really had them communicating via Profibus and Not via MPI…

They don’t say much and it seems that they don’t even know what they have done.

Best Regards

Edmund
 
To me it seems that either the CPU is not performant enough, and/or the bus (MPI or DP) is not performant enough.
You can try to tweak the 314C-2DP CPU by increasing the "Scan cycle load from communication" from the default 20% to 40%. If that helps, then the CPU is too slow. If it does not help, then the bus is too slow.
 
Hi again!
Just to satisfy my curiosity I have three more questions…

1. Why can is there only one connection under the CPU in connection reserved communication connections under other? Shouldn’t there be two?

2. And what does the checkbox “Cyclic Operation” in the WinCC Flex do, under connections?
One of the panels it’s checked, but only in one of them?!

3. Under connection for each panel (MP307/MP377) under node I can see the communication card CP343-1, but its chosen MUX-CP343-1? Whets MUX?
In the MP370 I can chose only CP343-1 as node but in MP377 there is only MUX-CP343-1 as suitable node...


Regards Edmund
 
Re 1 and 3: I think that it is possibly a socalled multiplexed connection. This is an option that is possible with CP343-1. With this only 1 connection between CPU and CP343-1 is used despite that there are multiple connections from the CP343-1 to external devices.
I have never used multiplexed connections myself, so it is just a guess.
I dont think it has any relevance with the performance problems.

Re 2: The cyclic operation should optimise the transfer of data between PLC and HMI if only 1 HMI device is configured. So you should disable cyclic operation for all HMIs.
 

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