RS NetWorx


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I just took up this assignment for setting up process control which includes Controllogix PLCs RSView32 HMI. They are all linked and controlled by RS Networx. The configuration is for a complete redundant client server system. So in case one HMI server fails the other takes over. I was informed that it took a long time to work out this system. Also the team has been advised by Rockwell that they cannot use VBA codes or any other similar stuff. But my problem is that for quite a lot of functions I need to use VBA and ActiveX. What troubles are we in for? Could somebody let me know from their experiences? Also the network in general is not-so-reliable and fails often. Rockwell seems to have informed that this happens when program files are downloaded into one of the CPUs. For me that is strange. Any suggestions would be helpful Thnaks Prem

Larry Lawver

Prem--- RSNetworx is a configuration software package, not a network. However, from your description, I'm going to guess that your network is ControlNet and address your questions. In my experience, ControlNet is extremely reliable when properly installed--- and any noticeable failure rate means the cabling is at fault. You may need to evaluate your cables with a tester from Allen-Bradley, Fluke, etc. If you are using redundant media, the network will barely work at all if the cabling isn't right. I'm mystified about your information about the use of VBA and ActiveX controls. Those are normally seen in process control, and you already have RSView32 in place. RSView32 can be a container for those objects, or it can act as a data server or client to your external application. Is there some aspect of the installed system that prevents you from modifying the RSView32 application? Or, are you forbidden from accessing the same communication package that RSView32 is using? Hope this helps! Larry Lawver Rexel / Central Florida
Thanks Larry, Well, I used the term RS Networx a bit skeptically. But you were correct in assuming that it is control net. To make things clearer, I have worked with this system before and considered it reliable. But the configuration here consists of total 3 sets of servers each with a redundant backup and its set of clients. The servers are configured in such a way that even if one set fails one of the other two sets(which normally do other functions) can take over the functions of failed ones. I agree that for this we need to make sure that databases are unique all over and some amount of programming to make sure that the switchover takes place in time is to be done. All is fine till now and it works. The problem starts with first , under this configuration the team has been advised by Rockwell not to use VBA and Activex.I can't figure out the reason. I tried some of these controls and I did not face any problem. I intend to go ahead implementing these and I wanted to know whether somebody has faced a problem (because now I am going against the advice of many who have not really tried it out and just taking a cautious step). The issue about reliability of the network came up because the answer given by Rockwell when the network had trouble(which is a bit too frequent) was that whenever anybody downloads a program through RSlogix into a CPU in the network then the Networx has to be run and this means disruption of the network and thereby affecting the system. Somehow my gut feeling is that the problem is somewhere else. Thanks For the Response Prem

Larry Lawver

Prem--- Downloading programs to a CPU is not a normal daily activity in a running system. Neither is running RSNetworx. Both activities indicate that the foundation of your process is being modified. After commissioning, these activities should be very rare. On those rare occasions that you must run those programs, CNet should simply work. However, if you are modifying fundamental network parameters, you should expect some disruption during the change. Why are you modifying this system so frequently? What are you seeing that makes you think CNet is failing? Larry Lawver Rexel / Central Florida
Sorry for the delay in replying Larry, I appreciate your support. Well, the system is being setup now and there are a number of programmers working on this and quite often there are parameters being changed. The network just freezes and we need to reboot the servers. I am still to get to the bottom of it. I am doing some trials right now. Well get back to you on the results. Prem