Katerina

Communication between a Robot and other machines

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Hello! I have written a plc program in ladder which is used for controlling/coordinating a production process in a manufacturing cell (including a robot , turning machine and milling machine and intermediate buffers).

For the control of the whole cell I am using a ‘central’ plc which sends and receives signals to/from the robot and the other machines. Moreover the signals that are sent to the robot and other machines are more than one .For instance, different signals sent to the robot referring to different movements which should made by the robot according to the program).

As you can see in the picture I have attached (which is only a small part of the 'central' plc program) Rst_I_A_T  is the output from the central plc (input to the robot) telling the robot to start a specific movement and Rfin is the input to the central plc (output from the robot) telling the central plc that this movement has been finished.

Questions :

1)      Generally when we want to control a robot in an industry which should be coordinated with other machines (and not have a continuous standard operation) do we use a separate plc connected to the robot?

2)      Is the way I am using Set and Reset for the input to the Robot Rst_I_A_T right ? I mean Rst_I_A_T is sent as a continuous signal to the robot and is reset by by the central plc when it receives Rfin from the robot. Is that right?

(Actually the task that I am doing is only in a theoritical level but I would like to be as right as possible!)

robot_communication.png

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Whenever possible we recommend an Ethernet connection between the PLC and Robot, with GE PLC and Fanuc Robots we ask for the GE proprietary Ethernet protocol called EGD (Ethernet Global Data) this is configured on each end to exchange any data needed. Other protocols recommended would be Ethernet/IP and Profinet.

As for Set/Reset I always recommend staying away from them except under controlled situations. IMHO it is better to use 'retentive' variables and/or holding contacts.

 

Edited by RussB

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On 13/4/2016 at 10:13 PM, RussB said:

Whenever possible we recommend an Ethernet connection between the PLC and Robot, with GE PLC and Fanuc Robots we ask for the GE proprietary Ethernet protocol called EGD (Ethernet Global Data) this is configured on each end to exchange any data needed. Other protocols recommended would be Ethernet/IP and Profinet.

As for Set/Reset I always recommend staying away from them except under controlled situations. IMHO it is better to use 'retentive' variables and/or holding contacts.

 

Hello! Thank you for your answer!
Regardless of using KEEP or SET/RESET and regardless of the communication protocol used , I would like to ask you :

Is the 'policy'  I have used for  signal transmission between the robot and the central plc is correct /realizable???

1) The central plc sends a signal Rst_I_A_T to the controller of the robot 

2)The robot controller receives the signal and performs the corresponding motion (Rst_I_A_T is still on)

3) The robot controller sends signal Rfin to the central plc when motion is finished (Rst_I_A_T is still on)

4) When the  central plc receives Rfin from the robot it resets the Rst_I_A_T signal. So the robot stops seeing it.

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personally i would not want to be the one to troubleshoot/maintain cell where PLC micromanages every single move of the robot. 

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7 hours ago, panic mode said:

personally i would not want to be the one to troubleshoot/maintain cell where PLC micromanages every single move of the robot. 

ΗI! Thank you for your answer!

As you can see, my knowledge in robotics and communication between controllers is limited. So, I really appreciate somebody's opinion who has practical experience in these issues!

So, if you had to coordinate/control a robot and and other machines which should work together properly (so as not to have collisions/deadlocks and mininmize waiting times ) wouldn't you use a central plc??

I have seen somewhere that in these cases they  also use a separate plc for the robot.

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All robot applications I work on have a PLC acting as a cell controller (90% of the cells I work on get delivered to Ford or GM and that is their requirement also).  The PLC coordinates all of the machinery and automation involving the material handling, operator interaction (HMI), and safety when a safety PLC is used.  Its much easier letting the robot be responsible for just what the robot is best at - single task motion and controlling end-of-arm tooling.  I find programming automation in ladder is much easier than trying to program automation in a robot scripting language.  The PLC is better suited to handle multiple asynchronous tasks where the robot is more suited for a single or list of sequential tasks.

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Robotics industry always interested me but I am not in this sphere. I always admire people who create robotics. 

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  There are different parts where you will have the process for the valuation to which it is going to have it for the most of the part to communicate with the machine and with robots because both are having the different work to do and this will be the best to have it just that the value and work of Robot is far better then the machine and  netgear tech support  which will guide you to find out the diffrents and will provide you the best information.

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