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Old August 15th, 2006, 09:32 PM   #1
oregonsam
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Question Micrologix on Devicenet network?

I am interested in the capabilities of Micrologix PLCs connected through devicenet to a Contrologix Systems. I assume that the Micrologix program would have to be entered/changed via the programming port, programming would have to be off line, and the program couldn't be monitored over the network. But this seems like a good, cheap possible solution where mostly local "intellegence" could control a machine.

What can the Contrologix system monitor and control over the network? Can input or binary bits be set via the network to create "global/local" control sceneario where the machine operation program could be in the Contrologix (global), or in the Micrologix (local).
I'm just curious how people have used the Micrologix in network control systems. Thanks in advance for any examples of this type of setup.
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Old August 16th, 2006, 12:10 AM   #2
automfg
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At my company we manufacture vehicles. We use a contrologix processor with 4 dnb modules in its local rack. off of these dnb modules we run out a flat communication cable the length of the production line (this cable also carries power for the dni modules and other devices). on this cable you can insert and remove taps. we connect dni modules to these taps. then we connect a micrologix 1000 processor to the dni module. we then use rsnetworx for device net to map the micrologix processor I/O data files. Now we have anywhere from about 20 to sometimes around 63 (via dni module nodes) micrologix processors connected on just 1 devicenet network. when we have a problem and need to get online with the micrologix processor we have to go to a main cp that is connected to the controllogix network to be able to get online with the micrologix to troubleshoot it while it is receiving information from the network. Now we can unplug the cable between the micrologix and the dni module to be able to hook up to the micrologix programming port but then we are no longer able to receive data from the network so we can not troubleshoot easily due to not being able to see what type of data is comming in from the network. and also yes you can change the plc program from the network or at the micrologix programming port (remember you must go offline to make changes to a micrologix due to you can not do online edits to this processor). The program can also be monitored over the network just like you are connected to the micrologix programming port.

We also use the flex i/o modules to add remote inputs and outputs at different locations in equipment that is located all over the plant. Also on some equipment we have directional control valves (air solenoid valves) manifold blocks that are controlled via device net this eliminates a lot of electrical wiring.

see this link from allen bradley for more info.
http://www.ab.com/networks/devicenet.html
http://www.ab.com/en/epub/catalogs/1...68364/5743866/
http://www.ab.com/en/epub/catalogs/1...4052/tab4.html
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Old August 16th, 2006, 04:25 AM   #3
Andybr
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I was not sure about this because we have very few Micrologix PLC's on our site so I have just checked and I can go online to an ML1200 via: Ethernet to CLX, ControlNet from CLX to CN2DN, DeviceNet from CN2DN to Net-DNI/ML1200. Messaging between the CLX and the ML is possible but there is more than one way of communicating via the DNI and it is important to avoid any conflicts. Some devices write directly to the Micrologix whilst others may write to the DNI.
How complex is the "Local intelligence" you refer to. If it is very simple you might want to look at something like Compact Block IO which supports DeviceLogix. This does not seem to be widely used but I have found it to be excellent for simple applications. In some instances I even have Compact Blocks running as stand alone PLC's.
Andybr
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Old August 16th, 2006, 05:34 AM   #4
Alan Case
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Have also seen a ML1000connected to a CLX DNet network via a Net-DNI.
You can monitor via ENet & DNet through to the ML.
Not my favourite way to do it. You are using 2 programming packages ie Logix 5000 and Logix 500
I suppose it comes down to how local you want your control, remembering that a CLX is very powerful and can easily multitask a lot of seperate machines.
Regards Alan Case
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Old August 16th, 2006, 01:57 PM   #5
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Actually you can monitor the program at the same time if I remember correctly. We had several stand alone pices of equipment that could be used standalone where the robot has hard wired signals to indicate request to enter status etc. or they could be grouped in a much larger system together and all controlled by a ControlLogix which was interfaced to a recipe system on a server. The ControlLogix rack had an Ethernet module in it and a DNB scanner. You could browse across the backplane and out through the DNB module to monitor the MicroLogix plcs which were connected to net-dni module. The MicroLogix plcs consisted of 1000 series units for simple stuff like rainfall sanders and 1200 series for the humidity/temperature control (Munters desicant dehumidifiers). I was able to take the Munters standard program and add a new subroutine to take care of the DeviceNet mapping I needed to remotely monitor/control the Munters unit. Anyway, it all worked very well and we ended up with standard designs, even if the equipment was utilized as stand alone or in a completly integrated package.

Darren
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Old August 16th, 2006, 08:11 PM   #6
oregonsam
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Thanks for the info.
The machine centers I am thinking about using the Micrologix for are not very complicated, and several units (variable number) are connected in series in the line. We currently use CLX and flexI/O with nodes at each couple of machine centers. It seems like cost wise, a micrologix "semi stand-alone" method might have advantages. The ability to standardize programming for machine centers and to partially test the stand-alone functionality without the network connected would also be benefitial.
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Old August 16th, 2006, 09:39 PM   #7
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I have used the Micrologix 1500 with a devicenet scanner in the rack set to slave mode on a similar application. The main PLC in my application was a SLC505 and this allowed me to pass all of the needed info over the network between machines. The other advantage is that if you found you would rather run the remote machine of the main PLC, you can install a 1769-ADN and power supply in place of the 1500 and scanner. This would turn it into a remote rack. On my application we also ran ethernet to all the PLC's and used ENI modules at the Micrologix PLC's. Now we can go online from anyplace on the plant network.
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Old August 17th, 2006, 08:12 AM   #8
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Also using carefully thought out UDTs (user defined data types) to create a standard interface for the network interface on the ControlLogix side would make it easy to design standard logic interface to that type of node (machine/equipment). Which eases adding/removing nodes if the line has to change over time.
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