PLC and moving data to a webserver

[widelto]

Goingnovation:
I do not exactly what you mean by "defining tags" , when you design your plc programs you define tags at the same time.
The OPC server (it runs on a PC) would then be a bridge between PLC and OPC clients, XLReporter is an excel add in opc client.

 

[goingnovation]

Goingnovation:
I do not exactly what you mean by "defining tags" , when you design your plc programs you define tags at the same time.
The OPC server (it runs on a PC) would then be a bridge between PLC and OPC clients, XLReporter is an excel add in opc client.

Sure, but the PLCs are already out there in the real world. Right now they are only polling to datapoints from the devices. We need to add 18 datapoints more per device. We'd need to add the tags to the PLC in order for the OPC to acquire the data right? The OPC Server can't connect to the devices directly, bypassing the PLC?

 

[widelto]

Yes, define your tags and then they will be visible by the OPC server.
The OPC can connect to the devices as long as they are already defined inside the PLC program.

 

[gclshortt]

I would look at AdvancedHMI for your data concentration. It has all of the drivers written for many PLC manufacturers including Modbus TCP and Modbus RTU.
https://sourceforge.net/projects/advancedhmi/
This is a free package. You can also use SQL Express 2014 as the database.
https://www.microsoft.com/en-ca/download/details.aspx?id=42299

Just a thought,
Regards,

 

[Dravik]

Sure, but the PLCs are already out there in the real world. Right now they are only polling to datapoints from the devices. We need to add 18 datapoints more per device. We'd need to add the tags to the PLC in order for the OPC to acquire the data right? The OPC Server can't connect to the devices directly, bypassing the PLC?

How do the PLCs poll data from the field devices?
Some sort of fieldbus?

 

[skeet]

Hello all,

I work with internet of things and am not a PLC expert at all - that's why I need your help.

I have a customer who's running a mix of PLCs to run a range of cooling machines. Each run a very similar program. They use 2-3 datapoints from the cooling machinery and a 4-20 mA input. The client now wishes to move this data out of the PLCs and into a web environment for data analysis.

1. How can this be done across different PLCs (Beckhoff, Siemens)?
2. Is there something like a " software agent" I can put on any PLC which can then extract the data already being retrieved for the program and forward it to a webserver?
3. We also need to extract a few additional datapoints beyond what will be used in the program. Is this possible without messing with the program?
4. Can this be done from the "software agent" I imagine to exist?

Thanks a lot for any help you can offer.

Go :site:!

Sounds like: http://www.osisoft.com/pi-system/

 

[harryting]

What HMI is it? A lot of HMI has built-in OPC server one can query from.

We use PI here but it's very very pricey since it's a process historian and the power of it is compressing the data to only what's meaningful.

OP, in genera, field device has to be interfaced with IO via PLC before the data can be made available. There are some devices that are networked and OPC UA compliant.

 

[goingnovation]

How do the PLCs poll data from the field devices?
Some sort of fieldbus?

Yeah, modbus Tcp and modbus RTU, depending on the model of the field device.

 

[goingnovation]

I would look at AdvancedHMI for your data concentration. It has all of the drivers written for many PLC manufacturers including Modbus TCP and Modbus RTU.
https://sourceforge.net/projects/advancedhmi/
This is a free package. You can also use SQL Express 2014 as the database.
https://www.microsoft.com/en-ca/download/details.aspx?id=42299

Just a thought,
Regards,

That sounds interesting. As I understand it, this has the drivers to connect to many different PLCs and also end devices. However, for the PLC to hand over the data I need, tags must be made on the PLC for that data.

Still, very nice with a "free" alternative. Any good experiences with this software to share?

 

[dploof23]

I have to second the Red Lion Data Station Plus. I am using one right now for the exact purpose you describe. It also has a built in web server that you can set up to display your data to anyone on the network. The database I created has Mitsubishi, Allen Bradley, and Omron PLC's networked to it and I have defined over 2000 different tags. There is no tag limit.

Hope this helps

 

[goingnovation]

I have to second the Red Lion Data Station Plus. I am using one right now for the exact purpose you describe. It also has a built in web server that you can set up to display your data to anyone on the network. The database I created has Mitsubishi, Allen Bradley, and Omron PLC's networked to it and I have defined over 2000 different tags. There is no tag limit.

Hope this helps

Hi, great with another vote for the RedLion solution. Just to make sure: In my case, the field devices are connected to the PLC via modbus. using this Red Lion Data Station Plus (RLDSP), I will still have to first define tags on the PLC, in order for the RLDSP to acquire the data right? RLDSP doesn't allow me to somehow pry the data out of the end devices, without touching the PLC, right?

Thanks again.

 

[Dravik]

Hi, great with another vote for the RedLion solution. Just to make sure: In my case, the field devices are connected to the PLC via modbus. using this Red Lion Data Station Plus (RLDSP), I will still have to first define tags on the PLC, in order for the RLDSP to acquire the data right? RLDSP doesn't allow me to somehow pry the data out of the end devices, without touching the PLC, right?

Thanks again.

If the DSP unit can talk to the field devices, It can poll them via Modbus in a similar fashion to the PLC. Now, if the field devices push data to the PLCs, then it gets trickier.
You'd have to do some testing to make sure it wouldn't interfere w/ your normal comms times of course.

 

[goingnovation]

If the DSP unit can talk to the field devices, It can poll them via Modbus in a similar fashion to the PLC. Now, if the field devices push data to the PLCs, then it gets trickier.
You'd have to do some testing to make sure it wouldn't interfere w/ your normal comms times of course.

Agreed, don't want to mess too much with the comms process as it is right now.

I'm sorry, but need to really get this straight: The field devices is connected to the PLC. The PLC is the connected to the larger network. Can I put the DSP in the larger network (with no physical connection to the device except the wires going to/from the PLC) and still poll the devices directly, without changing anything on the PLC, no new tags, no changes at all on the PLC?

 

[Dravik]

Agreed, don't want to mess too much with the comms process as it is right now.

I'm sorry, but need to really get this straight: The field devices is connected to the PLC. The PLC is the connected to the larger network. Can I put the DSP in the larger network (with no physical connection to the device except the wires going to/from the PLC) and still poll the devices directly, without changing anything on the PLC, no new tags, no changes at all on the PLC?

Short answer - No.

Long answer - For the Modbus RTU devices, No, not without an additional device for each connection.
For the Modbus TCP devices, You would need to make a change to the network to allow both devices to talk to your field device.

 

[goingnovation]

All, thanks for all your help. Based on your input, we've drafted a few options for the customer and will likely lean towards the RedLion option or the open source alternative.