Arguments against SCADA

It seems to me that SCADA packages are fine for displaying pretty graphics and being able to run some types of data acquistions.

My company is getting more requests for SCADA packages like RSView.
Then they come along and want huge databases, reporting, scheduling, etc.

My view so far is it you need a lot of Visual Basic routines that must be used then SCADA packages are not the way to go.

Some possible new customers have been burned with custom packages and having to pay high upgrades every time they need a change. They feel that going to SCADA packages will give them more control and they themselves will be able to modify the program if need be.

I have no problem with Visual Basic and interfacing to Allen-Bradley controllers, but to take a VB program that has thousands of lines and be expected to convert it to SCADA, the cost would be mighty high.

SCADA's work well if all you are looking for is a visual interaction, but if you have a very large application then they can become quite combersome. They do not handle storage and reporting of large amounts of data either. Usually you would need the SCADA and a storage package as well. IE RSView and Historian, Wonderware and INSQL. For the most part I think a SCADA system is a nice thing for the boys upstairs but the data is what is important to anyone who works on the systems.

Mark Buskell said:

My view so far is it you need a lot of Visual Basic routines that must be used then SCADA packages are not the way to go.

Click to expand...

I don't know that I fully agree with you here, but I can certainly understand where you are coming from.

Mark Buskell said:

Some possible new customers have been burned with custom packages and having to pay high upgrades every time they need a change.

Click to expand...

Or said another way - They feel that an off the shelf package is easy to upgrade/maintain, and can be made to fit the company needs without too much hassle (a oversimplification in my opinion). In contrast, a customized package can made to fit the company needs perfectly (at the time that it is written), but is miserable to upgrade/maintain.

With software patches/upgrades coming out every 3 months to a year, ANY custom code needs to be tested for compatibility regularly (read COST). Combine that with company needs changing rapidly (new products / new ways of doing business / etc), and companies will ALWAYS want the maximum flexibility with MINIMUM customization.

This is the ultimate enterprise software problem - whoever solves this issue will be a wealthy person indeed!

Invensys was trying to address this with their "Archestra" framework and "Open World" development suite. Their goal was open ended integration from the plant floor (SCADA systems like Wonderware) up to the enterprise level (ERP systems like Baan). They have certainly made strides in that direction, but my personal take is that there is still a long way to go! (They have since sold Baan, so who knows where they are going now.)

Rockwell has their offerings too (RS View, RS Bizware), and I'm sure there are others out there.

Bottom line, I can sympathize with you, but don't have any specific advice for you other than to recommend delivering systems with maximum future flexibility.

Good luck,

Marc

I use RSView to manage local trending, routine alarming and some other limited data collection (for c.y.a. purposes). I also have the 'pretty pictures' on it for the operators to stare at. Production and Line performance-related data is harvested by RSSql, and delivered to and managed by our IS department.

Most SCADA systems can archive data as CSV (Comma Separated Variable) files that can be pulled into any spreadsheet or database program.

Many of the packages also have scheduling and data anlaysis available, sometimes as an extra cost add-on package. Most of the high end packages also let you link your own C++ or VB apps to the SCADA.

Unless you are really doing something special, I don't think there is much you can do with VB that can't be done in a good high end SCADA. The advantage of a standard SCADA package for your customer (although you could care less) is that if you get hit by a truck they can still find someone fairly readily to maintain the system.

SCADA and data collection

My own experience with SCADA has been with Paragon TNT which has SQL commands and ODBC drivers. It will store data in just about any database format and will do local trending and history either from its own data files or from imported files. In the application I was working on I exported the data to a MSAccess database and then wrote a seperate Access application so that the data could be viewed and reported etc. off-line, without having to use a SCADA package for that purpose. So I had one SCADA system collecting the data and giving shop-floor trending, and one Access application that could be used by many (eg various managers and process engineers)to read the data.

For smaller SCADA applications I have written my own using Delphi (much easier than VB for database work) and again used Access for the database. This means that the Delphi front end can be completely controlled and the database is completely seperate from the data collection.

You should have a good look at Citect SCADA and Citect Plant To Business. They are both very good and work together.

Further, they both handle Active X and VB. Drivers for almost everything and strong OPC base. Highly recommended.

For reports, use an SQL data base or Excel etc. Have a talk to them. They are most helpful.

By the way, I know whrer your customers are coming from with respect to custom packages. One only has to have a look at what the likes of Honeywell charge for changes. WOW!!!!!

Hi Mark Buskell,

A bit of offtopic question, I understand you interfaces AB PLCs with VB, what is your approach, do you use third party ActiveX drivers, if yes which one of them. Which one is more cost effective and useful.

I was trying to evaluate, but unable to complete the exercise. I tried Ingear and vHMI. Found Ingear to be more easier to use. What is your opinion. Where can I learn more about VB and PLC interfaces

Thankyou

scada

Thanks for all of your help.

I have been using Automated Solutions software for a number of years.
I find it very easy to work with, I have used the DH+, Ethernet and Modbus versions that they have. They also have some type of SCADA package but I have not looked at that yet.

My expierence with RSView and VB has been a disappointment so far, it seems like their VB interface was thrown in as an after thought.

I had a simple call to VB passing a number 1-22 using an event. Well the VB App would quit working sometimes (1-3 days) and the computer would have to be rebooted. It happened on my Dells and also an ACER. I called AB and they could offer no insight as to the cause. Their fix was to use the Message Lookup utility. It did work by the way. Now another problem has arose, some of my records using the event function and saving the data to Access is not working sometimes. The customer has informed me that some of the batch results are not getting saved. Here I go again.

I have the RSView 7.0 software that is supposed to work with VB, but it seems AB as not got all of their bugs fixed after at least 7 versions of their software. I don't have a problem going with RSSQL but just disappointed that I may again have to switch from a VB call over to something else.

This makes me a bit leary about using any other SCADA package.
If it was displaying dryer zone temperatures I would not have a problem with SCADA, hence my pretty picture comment.

Footnote: We did convince the customer to go with our custom VB app on his job. I probably have at least 40 of these software apps running at various plants and that seemed to do the trick.

Mark
esystemsusa.com

The issue is not Scada.

It is quality software. Many of these VB addons are really VBA. I tried VBA once but I found out it is good only for small things. It was too slow. What you experienced is probably a 'memory leak'. I hate that term because it implies there is something wrong with the memory instead of the software. A 'memory leak' occurs when data is allocated but, not de-allocated after use. After a while the WINDOZE thinks it can allocate memory any more. If the 'low memory' situation can be detected then one could just restart the application. If not, WINDOZE appears to hang. I usually go into the task manager and start killing applications and useless threads and then WINDOZE comes back to life. The 'cure' is for the WINDOZE application developer to use a program that detects the memory leaks. This cost about $350-450 a year per seat. I bet many WINDOZE programmers don't bother because of cost so there are memory leaks.

Run the resource monitor. It will tell you if your memory is 'disappearing'.

Memory Leak

I considered a memory leak, here is the partial code. I talked to AB about this and we could not see how this could cause a problem.

I passed a 1-22 depending on the message. I used an event to trigger the vb routine.

Sub OperatorMessage(WhatMessage As Integer)
Dim opStep As Integer

opStep = gTagDb.GetTag("OperStep")
WhatMessage = opStep

On Error GoTo ErrHandler

Select Case WhatMessage
Case 1:
gTagDb.GetTag("OperMessage") = "Batch Process Complete"
Case 2:
gTagDb.GetTag("OperMessage") = "Batch Process Running"
End Select

gTagDb.GetTag("OperStep") = 0

Exit Sub
ErrHandler:
gActivity.Log "RSView32 VBA Error " & Err.Number & ": " & Err.Description, roActivityError
Resume Next
End Sub

Mark,

If You can't find a bug in your program lines, AND Allen-Bradley can't find a bug, THEN by proecess of elimination, could it be that your Event Call stops calling after some time period?

"I had a simple call to VB passing a number 1-22 using an event. Well the VB App would quit working sometimes (1-3 days) and the computer would have to be rebooted....."

Think about what events are triggering your calls. You are not using some clock time to trigger the event, are you? I once did an RSView data log every day at midnight. It took me awhile to figure out why it didn't always work ...the plant was often down at midnight and the computer was turned off!

I'm incredibly rusty on RSView but I had a similar problem some time ago. The code looked perfectly fine to me but the VB service would hang up after a while. The way I found it was to (somehow?) look at the error log which pinpointed the problem.

Sorry I can't be of more help.

Good Luck,

(8{)} ( .)

(Yosi)