Trying to fast track controlnet
- Thread starter nswu1
- Start date
Be aware that the firm ware is not always well tested. We went through a number of versions that fixed "control net noise" issues in various configurations. One version fixed the problem for 4, 7, and 13 slot racks the next version fixed the problem with redundant PLC processors. The latest version fixed the problem with 17 slot racks.
Watch out for redundant PLC systems with only one I/O rack. You will want to install two CNB modules in the rack (Rockwell recommended). When the redundant PLC system fails over, there is a short time period where the CNB in the I/O rack does not see any CNET traffic and resolves to its fail state and fails the rack for a few milliseconds. Any I/O point that is configured to fail off or fail on due to a CNB failure will go to that state.
Consider whether you want redundant CNET media and using the CNBR module. This would add another variation to the testing process. I have not used redundant CNET media.
See other threads on this website for similar conversations.
Watch out for redundant PLC systems with only one I/O rack. You will want to install two CNB modules in the rack (Rockwell recommended). When the redundant PLC system fails over, there is a short time period where the CNB in the I/O rack does not see any CNET traffic and resolves to its fail state and fails the rack for a few milliseconds. Any I/O point that is configured to fail off or fail on due to a CNB failure will go to that state.
Consider whether you want redundant CNET media and using the CNBR module. This would add another variation to the testing process. I have not used redundant CNET media.
See other threads on this website for similar conversations.
RSL
Member
I maintain a redundant (hot backup system) at our sight. It has close to 1000 I/O count. It uses 3 seperate ControlNets. It is truly "bumpless" during a switchover. None of my racks fault or go to "safe state". I have had virtualy no trouble with it at all. Yes, you have to have at least 3 nodes on a network for redundancy to work. It is not recomended, it is a must for it to work properly.
The redundant system does have several rules for proper implementation, but if followed it is rock solid reliable.
I also have several simple Controlnets on other systems. They are very easy to set up and maintain. I would not worry about setting up your new network if it is a simple remote I/O type system.
I have not used redundant media either. It is my understanding that it changes nothing in regards to how you set up your network. You just have to run 2 Coax's to every node instead of 1.
RSNetworx is a little weird at first. Scheduling the network and understanding NUTs, RPI's, etc. takes a little while to understand. Once you get it though it's easy.
Post specific questions and I am sure someone can answer them.
RSL
The redundant system does have several rules for proper implementation, but if followed it is rock solid reliable.
I also have several simple Controlnets on other systems. They are very easy to set up and maintain. I would not worry about setting up your new network if it is a simple remote I/O type system.
I have not used redundant media either. It is my understanding that it changes nothing in regards to how you set up your network. You just have to run 2 Coax's to every node instead of 1.
RSNetworx is a little weird at first. Scheduling the network and understanding NUTs, RPI's, etc. takes a little while to understand. Once you get it though it's easy.
Post specific questions and I am sure someone can answer them.
RSL
Last edited:
PhilipW
Member
ControlNet is rock solid and easy. The only problems I have encountered were on some very eary versions of firmware and RSNetworx about 5 or more years ago, and even then it was really just a case of following the directions carefully.
Rules:
Buy the correct coax (1786-RG6), all the correct 1786 components and buy the recommended Crimp and Termination ToolKit (1786-CTK). Standard TV RG6 coax is not good enough as it is not quad-shielded and tends to be too lossy.
Ensure you follow the simple, but essential trunk length/#droppers trade-off rules.
Like Devicenet, 85% of network problems will be traced to poor or faulty hardware technique.
Use the latest version of RSNetworx that is fully compatible with the firmware matrix of all the CNet adaptors.
Understand exactly what the NUT, RPI are and how to choose values that make the most sense for your application. Usually Rack Optimisation will be more than adequate for most Remote I/O chassis. Put any 1756-DNB's in the local chassis, otherwise they gobble up lots of bandwidth.
Set SMax and UMax to sensible values for your network. ControlNet gives the engineer quite a lot of freedom as to how they will weight the various bandwidth trade-offs to get the result best suited for the application, but overall you'll find that it has a LOT of capacity that can be stretched in a number of very useful ways. Normally you run into the connection limits of the 1756-DNB's before you run out of CNet bandwidth.
Have a look around on the KnowledgeBase site, I'm sure you'll find a document describing all this and more.
Rules:
Buy the correct coax (1786-RG6), all the correct 1786 components and buy the recommended Crimp and Termination ToolKit (1786-CTK). Standard TV RG6 coax is not good enough as it is not quad-shielded and tends to be too lossy.
Ensure you follow the simple, but essential trunk length/#droppers trade-off rules.
Like Devicenet, 85% of network problems will be traced to poor or faulty hardware technique.
Use the latest version of RSNetworx that is fully compatible with the firmware matrix of all the CNet adaptors.
Understand exactly what the NUT, RPI are and how to choose values that make the most sense for your application. Usually Rack Optimisation will be more than adequate for most Remote I/O chassis. Put any 1756-DNB's in the local chassis, otherwise they gobble up lots of bandwidth.
Set SMax and UMax to sensible values for your network. ControlNet gives the engineer quite a lot of freedom as to how they will weight the various bandwidth trade-offs to get the result best suited for the application, but overall you'll find that it has a LOT of capacity that can be stretched in a number of very useful ways. Normally you run into the connection limits of the 1756-DNB's before you run out of CNet bandwidth.
Have a look around on the KnowledgeBase site, I'm sure you'll find a document describing all this and more.
mgvol
Member
Like others have said, usually the biggest "gotcha" on a new system is the installation, particularly crimping on the connectors. Ask your distributor to get you a copy of the training video that shows how to use the installation toolkit and install the connectors. If your using a redundant system, make sure you won't have any firmware mismatches between CPU's & hot back-up or redundancy modules. Haven't done ControlNet redundant on Logix yet, but it was very critical with the PLC 5 to keep the F/W the same.
curlyandshemp
Lifetime Supporting Member
I second the crimping tool part. Most important!!. All C-Net issues we have had have been poorly crimped connector related.
Also avoid using PanelViews on C-NET. Gobbles up too much bandwidth, E-NET is preferred.
Ian
Also avoid using PanelViews on C-NET. Gobbles up too much bandwidth, E-NET is preferred.
Ian
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