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03/22/2021
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Hi,
Total newcomer to OPC, so please forgive me for any incorrect language used. I work for a software developer who has developed a portal platform for process management and automation. We've been asked to develop a dashboard and reporting solution for a client using Allen Bradley PLC's. In my research I came across OPC UA and would like someone to just confirm my understanding of OPC Server/Client to ensure we're starting off in the right direction.
- Initially I was expecting to be able to extract data directly from the PLC. Is this viable, possible and a cost effective route?
- If we were to create our own solution, I suspect we would need to create an OPC UA Server to talk with the PLC, and an OPC UA Client to extract the data from it. Correct?
- It seems that there is no standard for PLC to OPC Server communication. Am I correct? If so, I suspect that the only way to interrogate controllers directly is via an approved and most likely licensed API/Driver from each of the manufacturers we need to support. Correct?
- Is there an opensource version of Open UA server that is able to talk to a variety of PLC's? Initially I'm only looking at Allen Bradley, but there may be more later on.
- As our requirements are only to extract some basic data sets from the PLC, does anyone with knowledge of OPC UA have any suggestions as to how you would approach the issue? My concern is keeping the costs down as we dont need a full-blown solution.
- What PLC's does the opnsource OPC UA server support that is mentioned here?
Thanks in advance
Matt
05/30/2017
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Initially I was expecting to be able to extract data directly from the PLC. Is this viable, possible and a cost effective route?
Not all PLCs support OPC UA but industry is moving in that direction. If you using PLCs that do not support OPC UA you will need to use a protocol that they do support.
Note that many PLCs vendors offer OPC UA support as feature that must be enabled,
If we were to create our own solution, I suspect we would need to create an OPC UA Server to talk with the PLC, and an OPC UA Client to extract the data from it. Correct?
There are many gateway products that do exactly this. They translate numerous PLC protocols in to OPC UA for consumption by OPC UA clients. This allows the development of applications that only understand OPC UA.
It seems that there is no standard for PLC to OPC Server communication. Am I correct? If so, I suspect that the only way to interrogate controllers directly is via an approved and most likely licensed API/Driver from each of the manufacturers we need to support. Correct?
The OPC UA is trying to get there but it takes time. Given the nature of the industry the existing protocols will be around for a long time.
Is there an opensource version of Open UA server that is able to talk to a variety of PLC's? Initially I'm only looking at Allen Bradley, but there may be more later on.
The open source projects do not focus on the back end protocols.
As our requirements are only to extract some basic data sets from the PLC, does anyone with knowledge of OPC UA have any suggestions as to how you would approach the issue? My concern is keeping the costs down as we dont need a full-blown solution.
Option 1) look at a OPC COM to OPC UA gateway which is provided by numerous vendors with an OPC DA server for the PLC.
Option 2) Look at a PLC protocol to OPC UA convertor that is provided by numerous vendors.
You then write a OPC UA client that would talk directly to OPC UA PLCs but be bundled with another product for PLCs that do not support.
Since you have multiple choices you should be able to find a vendor that offers a solution that makes financial sense.
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