Need a solution

Hi Guys,

I mostly worked in the host side of SCADA and Automation systems so this is why I need your help regarding RTU and PLC side of the system. We have this Reclosers in the field which are talking to just to one of our SCADA realtime servers.

In other word we don't have redundancy for the Reclosers but the other field devices are OK. I mean both hot and stand by servers are polling them.

I'm asking our field guys (I'm the SCADA guy) and they are saying the reason is Reclosers are connected to modems through a serial connection.

First Question: Is this true? I mean do you admit that two SCADa servers can't poll a device connecting serially.

INFO: Communication Protocole: DNP3
Reclosers: Schnieder Electric Nulec (U series)
Modem: Cybertec (Series 2000)

Second question:
What's the solution?
I personally think we need to have an RTU (or PLC) like S7 200 with minimum features between our modem and Recloser so DNP3 addresses could be configured for both SCADA servers on this RTU/PLC. If you admit this then I'm looking for your advice about minimum configuration of this RTU / PLC

automan said:

I'm asking our field guys (I'm the SCADA guy) and they are saying the reason is Reclosers are connected to modems through a serial connection.

First Question: Is this true? I mean do you admit that two SCADa servers can't poll a device connecting serially.

INFO: Communication Protocole: DNP3
Reclosers: Schnieder Electric Nulec (U series)
Modem: Cybertec (Series 2000)

Click to expand...

As an old Schneider guy, yup, it sounds very much like our gear.

It has just the one modem, but that doesn't stop you from connecting the modem to a server and using that to parse out what you need to your various SCADA systems.

automan said:

Second question:
What's the solution?
I personally think we need to have an RTU (or PLC) like S7 200 with minimum features between our modem and Recloser so DNP3 addresses could be configured for both SCADA servers on this RTU/PLC. If you admit this then I'm looking for your advice about minimum configuration of this RTU / PLC

Click to expand...

I would use one of these:

http://www2.schneider-electric.com/...es/product-launch/powerlogic/user-guides.page

Connect it from your recloser via the modem (or Modbus) to the Ion meter, and use the PowerLogic Ion Enterprise to provide data to your SCADA system. It can be a pain to set up (have a Schneider rep at least setup the first one), but it works very well.

In the spirit of full disclosure, I am an ex-Schneider guy, so I am not going to make anything on this deal. But rather I'm suggesting that by keeping all of your gear Schneider, you pretty much make sure that they can't blame it not working on the other company.

Get them to first setup a recloser, an Ion meter, and Ion Enterprise to prove to you that it works before putting in your order.

Thanks rootboy,

First question again: Since the connection between SCADA system and Recloser is serial (through Modem), does this restrict the communication to just one server? You know nowadays most Scada realtime servers are redundant, it mean one is hot and the other one stand by. Our field guy is saying since the communication is serial, two servers can talk to the Recloser at the same time. Is that true?

Second Question:
and if that's true, what's the solution?

Ion Meter looks a very expensive device which would add heaps of functionality that I don't need. (You know Schneider Nulec Reclosers provide all that functionality remotely through WSOS software - this is a Nulec specific software)

Hi Automan,

What RTU's do you use in your network and how do they physically communicate back to your central servers (radio, microwave, etc)? Having a local RTU talk to the recloser over the serial line is probably the way to go, IF it supports the recloser's particular protocol?

How many reclosers are we talking about here?

is the modem line a leased line, and is there one modem which dials each recloser in sequence, gets data and then disconnects, or is the connection maintained, i.e. one modem at the server side per recloser?

I've seen old (very old) RTU setups where the base has a modem and simply dialed each RTU (there were only 2 mind you) every 15 minutes for an update. Cost the client a fortune in phone bills, so we finally converted both to UHF Radio.

automan said:

Thanks rootboy,

First question again: Since the connection between SCADA system and Recloser is serial (through Modem), does this restrict the communication to just one server? You know nowadays most Scada realtime servers are redundant, it mean one is hot and the other one stand by. Our field guy is saying since the communication is serial, two servers can talk to the Recloser at the same time. Is that true?

Click to expand...

Looks like it should be no problem, I got fooled by the (simple) block diagram so I downloaded the user manual instead. You should have an Ethernet port, a RS-485 port, 5 Rs-232 ports, and a modem port on your recloser.

Searching the manual for the term "Modbus" comes up with nothing. It appears that it will speak either WSOS5 & IOEX or "SCADA protocol" - whatever that means.

But since you are already talking to one, then connecting up to a second port should be no problem.

There is nothing preventing you from putting in a second modem on a separate RS-232 port and using that for your second server. The ports are setup to do this, but be aware that they are not electrically isolated and therefore you will need to keep the modem on the same power source as the recloser (see page 10-2).

Saffa said:

What RTU's do you use in your network and how do they physically communicate back to your central servers (radio, microwave, etc)? Having a local RTU talk to the recloser over the serial line is probably the way to go, IF it supports the recloser's particular protocol?

How many reclosers are we talking about here?

is the modem line a leased line, and is there one modem which dials each recloser in sequence, gets data and then disconnects, or is the connection maintained, i.e. one modem at the server side per recloser?

Click to expand...

Hi Saffa,
I'm not sure about the type of RTUs in substations but I know they're talking to master station through the SCADA LAN.
For the Reclosers it's a different story. They are talking through NextG network and there are couple of hundred of them.

If you are suggesting to have a local RTU talk to Reclosers, then what's the cheapest but reliable RTU you'd suggest?

And by the way Reclosers talking DNP3

rootboy said:

There is nothing preventing you from putting in a second modem on a separate RS-232 port and using that for your second server. The ports are setup to do this, but be aware that they are not electrically isolated and therefore you will need to keep the modem on the same power source as the recloser (see page 10-2).

Click to expand...

Thanks rootboy, one of the RS-232 ports is always dedicated and acupied for talking to WSOS software remotely so it leaves us with just one another RS-232 port which we are using for SCADA communication.

I'm wondering if we would be able to connect SCADA servers to the Reclosers through the Ethernet port you said they have.

ah, so the reclosers are on a 3rd party cellular network? that's all I could find when searching "NextG" on the net...

I think it really depends on the mechanism of how these re-closers are being communicated with at the moment. If they're being dialed like a normal PSTN modem then there's no reason your second server couldn't do the same, HOWEVER the call charges would likely go up... depending on whatever arrangement you have with the phone company. If they're on a data network then polling from the second server would probably not increase costs much at all.

Who sets up new reclosers / adds them to the poll queue? I'd talk to them, they probably know that side of the system even better than anyone guessing on here...

I would avoid rushing into installing RTUs at each recloser if you don't need to, obviously it'd be a big cost - couple grand a piece.

automan said:

Thanks rootboy, one of the RS-232 ports is always dedicated and acupied for talking to WSOS software remotely so it leaves us with just one another RS-232 port which we are using for SCADA communication.

I'm wondering if we would be able to connect SCADA servers to the Reclosers through the Ethernet port you said they have.

Click to expand...

Anytime.

Based on what I dug up from the net you should have five RS-232 ports. Is that not the case?

If it's practical, use the Ethernet connection instead.