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Read interval-OPCUA interface

Pioneer
Pioneer

Hi,

 

I have a question about setting read interval in OPC UA interface.  As the read interval is not defined as 0 ms, the error window pumps up.  The error is:

Revised read intervals in '.Models.Frame.OPCUA ':

from 10 to 50 millseconds.

.Models.Frame.OPCUA:The node ID refers to a node that does not exist in the server address space.

 

1.PNG

 

I need call back method to be triggered when the value changed from PLC code, which requires the read interval not a zero.

Does anyone have idea about this?

 

 

Best regards,

GEOZZ

6 REPLIES

Re: Read interval-OPCUA interface

Siemens Phenom Siemens Phenom
Siemens Phenom

At first I was confused about what object you are using. You named the OPC UA interface object "OPCClassicInterface".

Anyway, certain OPC servers have hard limitations, i.e. they are not capable of monitoring the items faster than a specific interval. Some OPC servers can be configured to allow shorter intervals. If you see the warning that the interval has been revised, the OPC server still works properly. It just uses the longer monitoring interval. You can avoid this warning by using that interval from the beginning.

If you set a read interval of 0, the items of the group are not monitored, but they can still be read. Plant Simulation will then always retrieve the value from the server. This can be slower or faster than monitoring the item by the OPC server and informing Plant Simulation about value changes (depending on how often you read the value, and how often the value actually changes).

To investigate the problem, I suggest you set a read interval of 0 and then read out the value. If the error still occurs, something is wrong with your item. Maybe it does not exist at all, or you mistyped the name, or use are using the wrong namespace. If you can successfully read the value, this would mean that the OPC server is not able to monitor this item for whatever reason.

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Re: Read interval-OPCUA interface

Pioneer
Pioneer

Hi,

 

Thank you for your response.

I fix the problem of namespace and change the OPC name.

 

I test to set 'read inteval=0' , plant simulation is able to read.

If the read inteval is set to other numer like 10, the error is:

 

Revised read intervals in '.Models.Frame.OPCUA ':

from 10 to 50 millseconds.

.Models.Frame.OPCUA: A monitoring filter cannot be used in combination with the attribute specified.

 

1.PNG

 

Does this suggest that the OPC server I use doesn't support monitoring?

 

Best regards,

GEOZZ

Re: Read interval-OPCUA interface

Siemens Legend Siemens Legend
Siemens Legend

Hello,

 

it seems, you are on the right track: yes obviously the OPC server refuses to accept the monitoring filter.

This is exacte the error message. As we do not see which item / item type you are addressing as part of the namespace 2, no more detailed hints are possible.

In general OPC server (independent of OPC classic or OPC UA) support monitoring.

You might look for more information on the OPC server side. The server part is not Plant Simulation!

 

Might be a good idea to contact Kepware as provider of the OPC server as well?!

 

Best regards

gepi

Re: Read interval-OPCUA interface

Pioneer
Pioneer

Hi,

 

Great thanks for your advice! The namespace is got from UAExpert, in which namespace is 2. Thus, I insert '2' as namespace in Plant sim.

1.PNG

 

About monitoring filter, does it mean ''To begin monitoring the PC's performance from the OPC Client application (including HMI, SCADA, Historian, MES, ERP, and countless custom applications) ''?

 

I will put more effort on the opc server side.

 

Best regards,

GEOZZ

Re: Read interval-OPCUA interface

Pioneer
Pioneer
Hi,
The problem was solved together with Kepware software engineer who developed a new patch for the version Kepware OPC v6.1. And finally, the virtual commissioning project by using OPC UA Interface was finished with a thesis report published at Chalmers. Can be referred to link <http://studentarbeten.chalmers.se/publication/251696-plc-integrated-discrete-event-simulation-for-pr...>. Thank you for all your help!

Re: Read interval-OPCUA interface

Gears Phenom Gears Phenom
Gears Phenom

Hello,

 

Glad to hear that you found an solution in the end to get the OPC working as expected.

 

Reading over key parts of your paper it is quite interesting to see that the number of elements is greatly increased by using the OPC communication to talk to a PLC compared to programing everything in the DES model itself.

 

As you might of been able to tell, this could be a quicker way of looking to optimism an existing complex system where you have access to the PLC code, and would double up by being able to test the PLC code changes being made, but in the time saved by not remodeling a complex system in plant sim you lose out when you are testing the system and needing to leave it to run the full time at 1x real time (yes you can run it faster but the communication times will be greatly affected, lets say it is 10ms communications and your running at 10x real time then every 0.1 seconds signals are processed instead).

 

So really at this stage it is more up to how you are planning to use the system and what you want out of it. I see it that every time I create a model I am creating a tool for people to use, and always ensure that I have the end goal of the tool in mind to ensure that it is fit for purpose and easy for the end user to use, be it me, other people where I work or the end customer.

 

We have also discussed a couple of times a multi purpose model, which can both take full advantage of being a DES model to run quickly and get data but through changing a checkbox will instead process signals and could be used by PLC programming to check their code works and compare it to the logic within the simulation normally to ensure it works in the same, but this is currently delayed due to need some more internal software to be produced to add another layer of modeling to the system which Plant Sim cannot easily handle (have tried before, but the single core architecture is the issue in this case).

 

JamesM