ControlLogix

[Guest Joe Lenhardt]

I was curious. I am connecting a VB application (running on PC) to a controllogix PLC. The PLC is then connecting to a robot that can only communicate (Controlnet, Devicenet, RIO or direct wire) I do not need to talk directly from the PC to the Robot. I was trying to connect to the PLC Via the DF-1 port on the controlnet, but i was told that i had to use ethernet in order to set up my Controlnet. Could use a little help here. I only have about 30 i/o total in the PLC and no analog.

[Ken Roach 194]

You are going to have to explain more about your system. ControlLogix and ControlNet are different but related product families ! Is your robot connected via a ControlNet network and 1756-CNB module to the ControlLogix system ? Is that connection a "scheduled connection" that needs to be set up using RSNetworx for ControlNet software ? Who is advising you to "use Ethernet" in any part of this system ?

[Guest Guest_Joe]

My local Sales office. I was informed that a PC Controlnet card would not be a good idea because the Controlnet is a scheduled network. He informed me that a PC - PLC Ethernet link would be better to communicate from the PC to PLC. I am also looking at AB RIO as the cost of ControlNet is quite large for my application. I have nothing running that would require a scheduled network.

[Guest Bowen]

Because ControlNet is a scheduled network, you require RSNetworx for ControlNet. You can't configure ControlNet through the DF1 port as there is not enough bandwidth; which was why you were told you had to use ENet. Cheapest solution is to go Enet to the Clogix, and then RIO to the Robot.

[Guest PhilipW]

Bollocks!! ControlNet works perfectly fine as an Unscheduled MMI network. It is NOT necessary to use RSNetworx to schedule anything UNLESS you are creating I/O connections. Now in most cases you are likely to finish up using ENet because the PC interfaces are so cheap, but don't be pushed this way if it's more convenient to use CNet. Only thing to watch is that you don't finish up overloading the 1756-CNB resources. I've used CNEt very successfully only several MMI applications where the amount of data flying around wasn't too onerous and it saved on an extra 1756-ENET card. Another area where CNEt is very useful is if you want redundant network cable. This is easy with CNet but much harder with ENet..

[Guest Bowen]

OK PhilipW, First off, his question was about connecting a robot to the plc; and he was trying to configure the ControlNet through the RS-232 port. Yes there are instances where you do not need to use RSNetworx, but those instances are for non-critical applications (i.e MMI which was the only thing you seemed to talk about in your post). I highly doubt the robot is set up to just send unsolicited messages to the plc, hence it has to be mapped as I/O, hence you need RSNetworx for ControlNet. Seeing as you seem to be so knowledgable and people like me don't seem to know what they are talking about, then there is no need for me to participate in these forums.

[Ken Roach 194]

Come on, folks, get some thicker skins. I've scheduled some ControlNet networks of very few nodes (okay, just two) via the DF1 -> CNB route. Agreed, there's a lot more bandwidth available when you're routing through an ENET or ENBT module, but for just one robot connection on a ControlNet, RSNetworx should work fine bridging through the processor. I was hoping Joe would post some details about the robot interface; I'm surprised it can do three different networks.

[Guest reply]

The robot Fanuc R2000 uses the R-J3 controller which can utilize either AB Remote I/O, DeviceNet or Controlnet using a card that slides into a rack on the Robot PLC. Setting up a scheduled network (controlNet) isnt very important, but bandwidth is (im being told). We have several systems that work from VB, but this will be the first to have a PLC in the middle.. or a Robot for that matter i guess. I am being told that the PLC is being used for I/O and Robot communications. I cant go into more detail than that im afraid. Thanks for all the answers. And i didnt post this to get people arguing.

[Ken Roach 194]

For the curious, here's the datasheet for the Fanuc robot's I/O options: http://www.fanucrobotics.com/datasheets/sc.../R-J3_%20IO.pdf

[Guest Bowen]

Just thought I would say I was out of line, and I apologize. I was having a bad day an unfortuantely took my anger out unprofessionaly.

[Guest PhilipW]

OK I take back the "bollocks"...fair cop... I should have added a ":-)". If I am reading this application right then I assume that there is a PC running a VB app, a CLX processor and the Fanuc robot. In this case I would be tempted to buy a 1784-KTC card for the PC, a 1756-CNB for the CLX chassis and the RJ3 CNet interface for the Fanuc. This way you will have superb performance and everything is simple to setup. Ken is most likely correct that RSNetWorx will be needed to schedule I/O between the CLX and the RJ3 card. The data flow to the VB application is most likely going to be unscheduled messaging via RSLinx. The serial port bandwidth issue then goes away too.