Info on Devicenet
Info on Devicenet
(OP)
Any advice on how to get started with using Devicenet?
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RE: Info on Devicenet
See Allen-Bradley publication:
http:/
Read all the Devicenet manuals available from Allen-Bradley.
http:
Realize Devicenet is souped-up CAN (Controller Area Network) so anything you learn about CAN is helpful when designing/installing a Devicenet network.
I purchased a CAN evaluation kit from Microchip that was VERY helpful in understanding the nitty gritty details of CAN and therefore Devicenet.
RE: Info on Devicenet
I guess you might say I dont like it. Unfortunately I have worked with it enough that I get a fair number of calls just to troubleshoot device net networks.
so back to my step back. There are certain instances where I might still spec it as the best option (rare, rare, rare). What is your application?
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Info on Devicenet
We once had an outside contractor install some equipment and he didn't use a dedicate power supply. The power supply was also being used to feed PLC inputs via auxiliary switches inside some local motor disconnects (lockout devices). Those motors were completely separate from the DeviceNet network (except for the power supply, of course). Some of those switches got some moisture in them and all hell broke out in the DeviceNet network.
I'd rather use RIO when and if possible. The programming and mapping is almost identical, but the wiring is way simpler.
RE: Info on Devicenet
I would suggest that ethernet i/p is the best and most sound networking architecture that ab has available. control net is ok, but you have to be very careful about your terminations and there are gotchas with that network also. Ethernet I/P is pretty straight forward and easy to terminate. I dont know of an ethernet I/P interface being destroyed by someone crossing some wires - may not work, but the interface still lives. Also good is profibus. It is associated with siemens and has a little learning curve, but it is a very solid networking solution with simple and forgiving wiring requirements. RIO is old and slow, but it is solid as a rock. Even if it is slow, it is generally faster than necessary for most I/O requirements. My only problem with it is that it is slowly but surely getting pushed out the door.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Info on Devicenet
RE: Info on Devicenet
Probably the best resource I have come across on this issue was a workshop I recently attended put on by Molex (Molex bought Brad Harrison, who had bought SST). They make scanner cards, but more importantly they make connectors, cables, splitters, junctions, terminators and repeaters. They offer these workshops all over the country and if you can find one, jump on it. The do not sell specific products during the workshop, they spend all of the time promoting good layout practices and going over pitfalls to avoid, troubleshooting methods, design tricks etc. to optimize your project success. I wish I had known this before I had done the projects that vexed me in the past, I now know what I did wrong. If they are not doing one in your area, call them anyway, they are experts on topology and configuration. I'm not throwing stones at A-B (today), but I think they were too focused on the bit twiddling and not enough on the physical layer when we ran into problems. As I see it now, I think they look at the physical layer as just necessary add-on accessories to their overall goal of selling their electronics and software. They don't actually make the network hardware they sell (much of it is brand labeled from Molex), so their approach to solving problems tended to be throwing more of their stuff at it and not looking at things like trunk lengths, drop cable sizes, power supply insertions etc.
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RE: Info on Devicenet
I once worked on a project where the electricians tywrapped Cat5 ethernet cable to inverter leads to make the cable tray look neat - needless to say the system had mysterious problems.
In my experience with Devicenet, most of my issues were due to my own ignorance. After I got the network up and running it ran great.
The following document from Allen-Bradley discusses the installation of the Devicenet physical components in depth:
http:/
One comment on Ethernet/IP - it is still non-deterministic.
IMHO, unless the system topology is designed with "jitter" in mind and the packets are "scheduled" properly, process critical applications such as the front end of a polyester spinning plant and nuclear power plants should be looked at skeptically with respect to Ethernet/IP. See the following paper:
http
RE: Info on Devicenet
Below is a list of hardware for my practice.
Control Logix 5561 slot 0
Ethernet module slot 5
1756-DNB slot 6 node 01
100-DNY41R node 04
I guess what my challenge first is I have not found a basic setup on uploading and downloading procedures required to get this running the first try. What has happened is without the procedures I have just kept at it trial and error long enough to finally get it right and have been able to see my input and output on both the DNY and in the logix. can anybody give me some input on my below procedures.
First I open my simple Control logix file and go on line, then I open RSNetwork for Device net, Go online and Browse.
My project will show up with the proper nodes displayed from this point it starts to get a little cloudy. Like i said earlier I have not been able to find documentation for this procedure so far. Do I start out by uploading from the device to the project, any help would be appreciated When I do get it right I cant seem to duplicate the success on the second try not sure if I'm overlooking something.
Thanks for your input
RE: Info on Devicenet
http:/
RE: Info on Devicenet
RE: Info on Devicenet
Dont forget the termination resistors. It looks like you have a small network so your system may actually work without them so they are easy to overlook; however, the missing resistors will cause trials and tribulations down the road.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Info on Devicenet
RE: Info on Devicenet
The panelview plus uses something Rockwell calls rslinx enterprise. The easiest way to setup your communications is to have a link to your processor on your development computer and use that to point to. I have been meaning to do some videos on this, but this work stuff keeps getting in the way...
When you open up your application, go all the way to the bottom (almost)of your explorer window and you should see RSLinx Enterprise. Expand that and click on communication setup. From there you can add a device shortcut and point to it on the right. There are two tabs on the right. Design and Runtime. If your access to the device is the same for your design computer as your runtime computer (recommended) then you can just click on the PLC you want to access and click the 'copy from design to runtime' button. when you create a tag in design, you will use the device shortcut you created as a prefix to your tags. checkout the help for the exact format or you can actually drill into your online or offline logix application to grab a tag that way. The design software gives you the capability to test your app so design a little and test - repeat. Every so often actually download to your hardware and test there. There are some differences as to how things will appear on the pv+ hardware.
Russell White, P.E.
Automation Technologies, Inc.
www.AutomationNC.com
Automation Help
www.PLCMentor.com
RE: Info on Devicenet