PLC connection Error

[ChristophTUM]

Hello Everybody,

i am working on a project at my university where we are measuring and regulating torque from a transmission. The regulation is done by a PLC (Siemens S300) and the recording of the torque is done by a seperate PC with a Compact RIO using Labview. The torque is measured by Labview using Renishaws, the Compact RIO and the seperate PC. 

The measured values are written in a DB in the PLC, then the regulation is done and at the same time we are reading a DB with the acutal numbers of revolutions. All the communication is done using DATA AHEAD SP7 toolkit the implementation is done the same way as described in the examples given by DATA AHEAD. The communication between Labview and the PLC is working fine except one thing. After a thew minutes, sometimes only 2min, sometimes 60min the connection is interrupted and the the write Block from the SP7 toolkit, which writes the torque into the DB in the PLC gives us a error back, which says "No answer from PLC to request" (as described in the picture). 

I really hope somebody knows at least something. The last two weeks we tried everything that came in our minds, but sadly we haven´t found the solution yet.

Thanks 

Christoph

[IDASYAN]

Hi there,

It seems like the issue is not static , it would make harder to get to the problem.

Have You tried to change the program on the PLC to work correctly with Your interface and alarming program that You created in LabWIEW?

This link may help You...

[Greil]

Hallo Christoph,

hast du schon eine Lösung? Ich habe das gleiche Problem und suche noch etwas, was wirklich hilft.

Als Zwischenlösung habe ich bei diesem Fehler bis zu 15x Retry und eine Wartezeit 200ms. Aber trotzdem ist der Fehler 6012 wieder nach 17 Stunden durchgerutscht.

Aber ich brauche etwas, was wochenlang stabil läuft.

Auch eine VI Properties > Execution > Priority = time critical priority

hilft nicht.

[rolfk]

Have you tried to contact Data Ahead? As it is their product they would be the first contact point for such support questions. Not knowing the toolkit myself I have not a good idea to the cause of the problem. Especially since they don't return the native TCP/IP error but rather a custom Toolkit error, so it is hard to know if this is caused by a timeout error on a read, or some other more serious error. The error could also be due to the fact that it is using a 300 series PLC. The S7 protocol is a Siemens proprietary protocol that they invented and used for all their S7 series PLCs but there are noticeable differences between the different models that require specialistic handling of some communication details depending on the model. The Data Ahead toolkit may have been predominantly tested on the more industrial grade 1200 and 1500 series of Siemens PLCs and only received minor testing for other models of the S7 line of products.

I have developed a library for the S7 protocol in the past myself but have abandoned the idea to make it into a released product. It worked for the 1200 series of products which our customer was using and likely would have worked for the 1500 as well, but I have reasonable doubts that it would work as is for the 200 Logo, 300 and 400 series or any other models that support S7 communication protocol.

And the S7 protocol as publically known does not support the optimized DB items as available since TIA 11 or 12 for the 1200 and 1500 series. I'm not sure if the Data Ahead library supports the extended S7 protocol that would be needed for support of this.

[girish_jadhav]

Hi Christoph,

We have done something similar in our lab but it doesn't use the DATA AHEAD toolkit. We are sending and receiving data from/to the database over ethernet TCP/IP. May be you can take a look into that?