>>Message imported from previous forum - Category:ClearSCADA Software<<
User: florian, originally posted: 2018-10-25 20:08:09 Id:297
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.
**_Hi all ClearSCADA experts,_**
**_We got an issue with the ClearSCADA 2015 R2 at our site in which the ClearSCADA responded very slow when communicating with M580 PLC hot standby. Whenever I change in ClearSCADA for instance, changing a setpoint or selecting a button, or process value change in the field, the PLC will take the effect immediately, however the ClearSCADA will take about 9-10 seconds or even more to change in ClearSCADA screen. It is really slow and unacceptable for the process plant like water treatment plant that we are commissioning even though the high spec M580 is put in place. In contrast, with the same ClearSCADA but communicating with M340 and Premium PLCs, the response time is much faster, about 3-4 second to take the effect._**
**_What are the reasons causing this issue? We would like to know the solution to improve it?_**
Have you contacted the support team? (See the Help/About box).
Maybe you are using Modbus, or OPC via OPC Factory Server (OFS)?
What are the scan rates for OFS and for ClearSCADA?
The support team may ask you for log files.
**_I am using Advanced Modbus driver. I already contact Schneider and they requested some logs file to investigate._**
**_My gut feeling is some thing with Modbus driver scanning. My PLC program is quite big with quite number of sequences and each sequence contains configuration word, status word and strings which were assigned to the PLC addresses about 150 %MW in length. I am thinking that the ClearSCADA server (Modbus driver channel) is struggling to scan every single point in PLC at the same retrieval intervals. I plan to separate the scan intervals for different sub-systems in PLC._**
**_Want to know from forum anyone got the similar issue._**
How have you arranged your Modbus registers?
Are they all sequential?
Are you using Ethernet for the Modbus communications?
My suspicion is that the reason your Modbus communications is slow is that you have not optimised for the Modbus protocol (which is efficient at doing sequential register reads, but very inefficient when reading from lots of individual locations).
The solution would be to reconfigure your Modbus register layout so that reads are sequential.
You can add in dummy points to ClearSCADA to read registers in between those that you actually care about to improve performance sometimes.
**_I am using Ethernet communication. The register in PLC is sequential._**
**_I have sent IO logs to Schneider support and they replied as below:_**
**_"It looks like almost all of the read requests get the responses back very promptly within a fraction of a second. This indicates that the communication from the driver towards the PLC is fine and very responsive. I assume the delay you mentioned is a consistent delay. Perhaps you can give a specific timeframe whereby the value of a specific point changes so that I can trace that one point._**
**_If you are saying that the value is not being displayed/updated in the mimic in prompt manner, perhaps the mimic itself has some configuration which might have caused this?_**
**_Can you check by creating new mimic, with reasonable scan rate, to show one of the point value? This is to check whether or not the existing mimic behaves differently than this new mimic. If this new mimic displays the value promptly, then the existing mimic might have some script or configuration or perhaps the scan rate that needs to be modified."_**
**_Today, I have created a new mimic and tried to simulate an analog value in PLC to see how it is updated in ClearSCADA. It's very strange that the response times for updating on ClearSCADA since value has changed in PLC are very different, it was from 2 seconds to 10 seconds. I am not so sure why it is. It's not constantly updated on ClearSCADA._**
**_Any idea about this?_**
Start a new application/database. Add the comms and start by adding just one analog value from the PLC. Test the response rate. Add another and test again. Do that with 10 values. How is it looking?
I am guessing there is logic / scripting that is running in the current app. that may be affecting the response rate on the screen. Starting from a fresh new app should make it clear if its the driver and or the screen response rate that is an issue without any scripts / logic to interfere.
Let us know what you find.
Also make sure your ViewX is connecting to the Main and not a Standby server, server syncing on a heavy system could see update rates around 10 seconds.
**_Yesterday I tried to use another database from another project and created an analog point to map with PLC and did some simulation to change value in PLC and observe the response on ClearSCADA. That response is quite good 2-3 seconds to response from PLC change._**
**_Later I realized that the database I tried only has 10,000 points which is much lesser than my current database is 37,000 points. So I think that the current server hardware config can't cope with the bigger database._**
**_This morning, I have updated the ClearSCADA to the latest update Aug 2018 as recommended by Scheneider Tech support. It seems the performance is worse than before. The response time is much much longer 20-25 seconds sometimes up to 50 seconds for any action. I have checked the CPU/Memory usage, it shows normal usage._**
Try looking at how busy the database is.
Use the Server Status tool, log in to the server and open the General/Locks page.
Select the second row (Metadata) - scroll to the right and look at the '% Time In Shared Lock' value. When this gets above 70% the database is busy, and when above 90% performance will be slow. You can right-click to reset the stat and then watch it change as things happen.
Potential causes include Logic, Calculation Point and Drivers being configured 'too fast for your PC'.
If the lock % is low, then your problems could be the PLC itself, your network, or just incorrect configuration such as long scan intervals.
**_It seems I found the issue causing slow response in ClearSCADA. This morning, I tried to duplicate another channel/station which I use to communicate with PLC. So I have two channels/stations with the same parameters, the only different is ID station. Then I moved half of the database to new channel/stations which reduce significantly the response time. All the points are quite responsive now._**
**_I am not sure why one channel/station is quite struggling with large database. I need to check with Schneider about this._**
**_Thanks for all advices._**