Pushing data to SCADA

Hi

Does anyone know a way/protocol to push data from a remote PLC (over internet) to an HMI package (such as RSView or any other). It is for use with report by exception or when the PLC is not addressable via a public address. Any ideas welcome...

As a rule, it's not the PLC that pushes data to the HMI, but rather the HMI that PULLS data from the PLCs

Either use VPN access (still, with control residing on the HMI), or use an event based dial-out from the PLC. The biggest problem with event based dial-out, is that it can take time for a data-server to wake up after it goes into slow poll mode.

Erik vdH said:

Hi
Does anyone know a way/protocol to push data from a remote PLC (over internet) to an HMI package (such as RSView or any other). It is for use with report by exception or when the PLC is not addressable via a public address. Any ideas welcome...

Click to expand...

Strange question... isn't it? What's your task? What hard- software will be used? Why you want to connect opposite?

OZEE said:

As a rule, it's not the PLC that pushes data to the HMI, but rather the HMI that PULLS data from the PLCs

Click to expand...

- It's quite right way.

If you told RSView about it seems you're intrested in AB. So... if you have AB's PLC, SCADA (for example Rockwell's RSView) - it's easy.
Or I'd not got the sence of your question...

Yeah, JJ's on track. What requirements/problems are you trying to satisfy?

As for me, it not seems that the question is strange. Because it is rather widespread problem - acquisition of data through the Internet from remote PLC. But the traditional approach with assignment a fixed external IP address for each partaker is very costly. In other words - only one fixed IP to which remote PLC-s accost for data's exchange would be appreciated due to costs savings. Or even without any fixed IP at all, only DNS based approach would be super.

Click to expand...

yes Zova - that is the problem I am trying to solve. To gather data from remote PLCs over the internet. With a local network you don't pay for data so polling continuously does not 'cost' as such. With lower quality links and the internet in general, I would like to optimise the data usage (hence report by exception). That way, data is only sent when there is something to report. I think they do it all the time in the world of RTUs and SCADA system but I don't know how. I have a Micrologix 1100 and haven't chosen an HMI yet.

Either use VPN access (still, with control residing on the HMI), or use an event based dial-out from the PLC. The biggest problem with event based dial-out, is that it can take time for a data-server to wake up after it goes into slow poll mode.

Click to expand...

I would be interested in some more detail on how to set this up, especially a VPN with only a PLC at one end...

I think you're missing the subtlety of what we're asking about. Acquisition of data through the Internet from a remote PLC is a solved problem - use an OPC data logger like FactorySQL. Your IP addressing issue can be dealt with using a free dynamic DNS service.

The point questioned is why he needs to push (initiate) the data from the PLC rather than poll it from the data logging application.

zova said:

First of all I congratulate J.J for his first post.

As for me, it not seems that the question is strange. Because it is rather widespread problem - acquisition of data through the Internet from remote PLC. But the traditional approach with assignment a fixed external IP address for each partaker is very costly. In other words - only one fixed IP to which remote PLC-s accost for data's exchange would be appreciated due to costs savings. Or even without any fixed IP at all, only DNS based approach would be super.

I vote for Pushing data to SCADA !

Click to expand...

Erik vdH said:

I think they do it all the time in the world of RTUs and SCADA system but I don't know how. I have a Micrologix 1100 and haven't chosen an HMI yet.

Click to expand...

It's not exactly pushing data to the SACDA it is sending an unsolicited message to the SCADA to tell it to poll the RTU.I have ever only done this over a telemtry or dial up link, but i suppose it would work over an internet link. You would use a RTU and SCADA using DNP3 protocol, i don't think you will be able to do it with a 1100 and a typical HMI although i think it was mentioned that the new micrologix 1400 has DNP3.

There is a lot involved but basically you can set the SCADA system to poll the RTU's at a set interval (say once every 2 hours) and also you set up your RTU for unsolicited reporting.
The unsolicited you would set in the RTU would be the memory on the RTU at a certain capacity or if a particular alarm is triggered. The RTU will send an unsolicited report to the SCADA system and the SCADA will poll it to retreive the stored data.
There is a lot of other things to take into account so that the buffered data at the RTU does not fill up too quickly, like if you were monitoring the level of a tank you would not want to log every 1% movement.

Check this out:

http://www.automation.siemens.com/net/html_76/produkte/060_produkte.htm

Nick B said:

Check this out:

http://www.automation.siemens.com/net/html_76/produkte/060_produkte.htm

Click to expand...

SINAUT products are parts of traditional approach,

http://support.automation.siemens.com/WW/llisapi.dll?func=ll&objId=29698735&ClusterID=21959422&nodeid0=10805055&load=treecontent&subtype=133000&lang=en&siteid=cseus&aktprim=0&objaction=csview&extranet=standard&viewreg=WW&display=p

so should be out of the scope.