Remote connections

sapoleon

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S
Join Date
Aug 2003
Location
salta, salta
Posts
315
hi to all.

I have to make a connection to get data with an SCADA from some PLCs. The thing is, that the PLCs are located in a remote facilities, some kms away.
There is internet where the PLCs are located.
We found a solution, with a system that connects the PLC to an internet site, and that internet site, provides an OPC server to be installed in the SCADA PC and read the desired tags.
The 'problem' is that for the use of the site, and the OPC you have to pay some 20uss for each PLC every month.
So, what we are looking for is some system or method without a monthly payment.

Does some one has any ideas or used something like that?

Thanks
 
Pretty much any TCP/IP OPC server should work across the Internet since both sides have access. Only broadcast/multicast type applications won't (typically not applicable here). You should be able to use pretty much any SCADA package - not just an Internet based subscription service. Look into VPNs to provide a secure tunnel.
 
Last edited:
surferb,

That's ok when you have a PC with OPC server near the PLC and you whant to read that OPC from another PC with the SCADA.
I just have a PLC without PC in another city. I have an internet connection through an internet server, and modem+router, but I don't have a PC to make the connection directly to the PLC.
 
It might help to let us know what brand/model of PLC you are trying to connect. If the PLC has ethernet capability then you will be able to attach them to a network and gain access to them remotely.
 
The VPN puts the PC (with the OPC server) "on the same network" as the remote PLC over the Internet.

sapoleon said:
surferb,

That's ok when you have a PC with OPC server near the PLC and you whant to read that OPC from another PC with the SCADA.
I just have a PLC without PC in another city. I have an internet connection through an internet server, and modem+router, but I don't have a PC to make the connection directly to the PLC.
Click to expand...
 
Yes, VPN is the way to go. I have 3 facilities which are remote to each other, and all can access each others data through a vpn tunnel between the 3. However, you also state that they are a few kms away from each other. Do you have line of site? A ethernet radio can easily cover 10 k at decent speeds. Fill us in with a few more details
 
Kyle's right on point. You can also do multipoint drops with Ethernet radios to get additional range.

ghettofreeryder said:
Yes, VPN is the way to go. I have 3 facilities which are remote to each other, and all can access each others data through a vpn tunnel between the 3. However, you also state that they are a few kms away from each other. Do you have line of site? A ethernet radio can easily cover 10 k at decent speeds. Fill us in with a few more details
Click to expand...
 
hi,
The PLC is a SC500 from ABB. It does not contain Ethernet.
The distances can be up to 200km.
We do not need too much data from each PLC. It's going to be 20 to 30 words from each PLC, and the ratio that we need to read them is more or less once per minute, but it maybe negotiable to once every 5 minutes.
Once a day, we need to send a recipe with 20 parameters (words).

The SCADA is going to be Cimplicity 6.1 and in a near future Cimplicity 7. But in any case, we need to use OPC so the SCADA package is irrelevant.

I think we can slowly change (if realy needed) the PLCs to CPUs with ethernet capability, but even thou, I don't see how they are going to 'dial' a VPN. I remind you that we don't have PCs in the place where the PLCs are mounted. It's just the PLC in it's electrical board.

thanks again for your help.
 
I don't see how you could possibly expect to accomplish this without Ethernet or a PC. Once Ethernet PLC might be sufficient if you can set up inter-PLC communication.

The VPN connection can be peristant. You would set up a VPN capable router on each end and set up a "gateway to gateway" tunnel.

sapoleon said:
hi,
The PLC is a SC500 from ABB. It does not contain Ethernet.
The distances can be up to 200km.
We do not need too much data from each PLC. It's going to be 20 to 30 words from each PLC, and the ratio that we need to read them is more or less once per minute, but it maybe negotiable to once every 5 minutes.
Once a day, we need to send a recipe with 20 parameters (words).

The SCADA is going to be Cimplicity 6.1 and in a near future Cimplicity 7. But in any case, we need to use OPC so the SCADA package is irrelevant.

I think we can slowly change (if realy needed) the PLCs to CPUs with ethernet capability, but even thou, I don't see how they are going to 'dial' a VPN. I remind you that we don't have PCs in the place where the PLCs are mounted. It's just the PLC in it's electrical board.

thanks again for your help.
Click to expand...
 
I don't see how you could possibly expect to accomplish this without Ethernet
Click to expand...

Like I said in my first post, there is internet, what ther is not is a PC. And yes, I know I have to 'anyhow' put the PLC in the internet.
I know the existence of VPN and its uses.
What I do not know, is how to get to a VPN or make a VPN connection from a PLC with or without Ethernet capabilities.
Is there some device that make that trick? maybe with a serial connection to the PLC or if not when I have a PLC with ethernet, how should it get into the web or how can it receive the connection?
 
What networks are these PLC's currently on? There are protocol convertors from pretty much any type of network to ethernet which may work for this application.

surferb is right about buying a few VPN capable routers and connecting the PLCs to them directly.
 
It seems that the router with VPN is the way to go.
Does someone knows one that can be mount outside? That's to say in a cabinet not so well protected of the rain and sun?
 
I don't know if this would work or not, but I thought I'd throw some ideas out there. You can use VPN routers to create and maintain a persistant VPN tunnel to the PLC. Then, assuming your PLC has an RS-232 serial port, you can use a serial port server or an industrial serial to Ethernet converter to put the PLC on the network. The SCADA computer should then be able to connect to the serial port server over the VPN, and treat it like a normal COM port. You should then be able to set up your OPC software to use this COM port.

Disclaimer: I haven't tried a setup like this, and a lot is dependent on the configuration of your PLC (ports available, protocols available, OPC server settings, etc.)
 
A "protocol converter" is called a gateway. You may be able to find an Ethernet->Serial deal. Alternatively, you could get an ethernet module for your PLC or a single "Ethernet PLC" - again, assuming that you have backside communication worked out. Looking back - JGreen has workable options.
 

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