PLC5 How does the # of nodes being monitored affect DH+ performance

We just had a sub (node) lose communication on our DH+. My co-worker mentioned that this might be due to the # of RSlogix applications that were opened at the time. We had 5 RSLogix5 windows open simultaneously, monitoring 5 different nodes on the DH+ in one pc and another 2 on another PC on the DH+. My question is how this would affect the performance of the DH+. I originally thought that it would'nt have a major affect on the DH+ but after thinking about it for a while I'm not so sure. We have our DH+ configured at 57,600. We are talking about this as I type this post and a few more ?s have come up. Does rslinx need the token to communicate with the processor that it is online to? How does the # of RSlogix opened on the DH+ play into the grand scheme of things wrt the DH+? Thanks!

I've seen this and proven it to myself before. With us the magic number was 3 open online copies of logix. Anymore than two and it started dropping nodes.

I don't know enough to explain to you why, just know you aren't imagining things. This can happen

Thanks allscott. Anyone else care to weigh in on this one?

I have never tried more than 3 instances at once per DH+ network, but I do know that RSLogix can put quite a load on a network. First, RSLogix uploads the entire PLC memory, then every address location that is opened for viewing while online in RSLogix is being repeatedly polled.

I have seen a network loaded up to the point that a single programming terminal would kill the response rate of the HMIs on the same network.

With DH+, if you get more than 6 or 8 nodes, you should be very careful to optimize all communications to avoid this.

How many devices are on your network aside from the programming terminals?

OkiePC we have 2 PCs and 8 PLCs on our DH+.

For reference, the network I was referring to had 6 SLC's 2 PLC 5's, 7 panelviews, One PC node gathering data, and our programming PC.

thanks allscott. thats quite a bit more traffic than what we have. I'm still looking into it. If I find anything out I'll post it for future reference.

One thing to be aware of.
When you open another program file in RSLogix, then the allready opened files will stay open. Notice the number of "tabs" in the bottom of the ladder editor.
RSLogix then polls all the data that is necessary to update all the opened files.
I regularly shut down the ladder editor window and the open it up again with only the file(s) I need to view at a given time. If I dont, the response of the online display will slowly decrease.

Thanks JesperMP. I never thought of that but after reading your post I sat and thought about it for a few moments and it becomes painfully obvious. The more information you are asking the DH+ to give you, i.e. 3 RSLogix tabs all with lets say 5 ladders open, the more traffic you are generating that needs to be sent on the highway. I'm getting an appreciation for the amount of work our DH+ does at our plant. It is not uncommon to see several applications of RSLogix open on both of our PCs with several ladders open in each application. We don't usually have a problem. I'll have to pay more attention to it. I keep meaning to call AB and ask for some detailed info so I can post. I've been really busy at work. Should slow down soon and I'll get some time. Thanks again!