Slave PLC to Master KR C4

    Hello, this is my first post on this forum :smiling_face:


    We have recently purchased a Kuka KR C4 with the KR 70 R2100 Robotic Arm, the goal of the project is to have an end effector with several different components (Solenoids, Motors, Sensors, Heaters, etc) the idea is that all those components will communicate with a PLC instead of an extra kuka axis (not enough axis', plus its less expensive as far as I can tell). We want the PLC to be a slave to the KR C4 however this poses a few issues. The PLC we are looking at (Automation Direct P1-550) only supports Ether/IP & Modbus TCP/RTU/ASCII but EtherIP/Modbus TCP port is already used to communicate with a motor driver on the end effector tool, so we only have Modbus RTU/ASCII left as viable ports. Meanwhile, KR C4 only supports EtherCat, Profibus, and DeviceNet. Once again we would like the PLC to be the slave to the KR C4 Master but communication differences and the fact that we are all beginners in PLC and KUKA make it very confusing. As far as I can tell I'm going to need a converter/gateway, but there are many options and I'm not too sure what make a good gateway and what make a bad one. Are there any ideas or tips on how to achieve this? Thank you for your time!

  • Lemster68

    Approved the thread.

    1. The robot does not have to be the master -- it's entirely possible for the PLC to be the bus Master to the robot and all the EOAT components, but still let the robot control the process. At the Bus level, Master/Slave (Scanner/Device, these days) is purely about getting communications working. It has nothing to do with which unit is in charge.


    2. Is there a reason you can't buy the Ethernet/IP option for the robot?


    3. For EIP and ProfiNet, KUKA sells a "basic" option (Device Only), and a more advanced option (Scanner and Device). You need to check which one you have, and make sure to buy the correct one for your bus architecture.


    4. AnyBus Gateways exist to bridge one bus type to another. It might be possible to buy one that bridges Profibus/Devicenet/EtherCat to Ethernet/IP, but l you may have to have special configuration software to make it work.

    Quote

    The PLC we are looking at (Automation Direct P1-550) only supports Ether/IP & Modbus TCP/RTU/ASCII but EtherIP/Modbus TCP port is already used to communicate with a motor driver on the end effector tool,...

    what does that mean exactly?

    "port is used" does not tell much. one port could be used to communicate with multiple devices on same network. that is where ethernet switch comes in...

    the question is how exactly it is used? is it EthernetIP or Modbus/TCP? is it master or slave?


    Quote

    Once again we would like the PLC to be the slave to the KR C4 Master

    not sure why is that important or even an issue.... it simply tells who controls communication. messages still go both ways regardless of role. so if your PLC is EthernetIP master and motor drivers is etherentIP slave, you would probably want KRC to be also EthernetIP slave so it can serve same master.


    Quote

    As far as I can tell I'm going to need a converter/gateway, but there are many options and I'm not too sure what make a good gateway and what make a bad one.

    first you need to have a clear idea of available connectivity options and roles of the interfaces as well as size and type of signals to be exchanged. then you can start looking at some gateway as a possible solution.


    Quote

    For EIP and ProfiNet, KUKA sells a "basic" option (Device Only), and a more advanced option (Scanner and Device).

    Actually as far as i know, KUKA offers such options for ProfiNet (M/S or just -/S).

    But EthernetIP is always a M/S version.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    1. Alright ill keep it in mind, although the reason we want to use the Kr C4 as the master is to take advantage of the KUKA training and program everything through the Kuka Software.


    2. Its been purchased already, so its pretty concrete that I need to use EtherCAT/Profibus/DeviceNet unless I'm missing something critical from the KR C4 Manual


    3. Alright I'll check that


    4. I may need to look at a different PLC if the Ethernet Switch idea proposed by PanicMode does not work out. From looking at the Anybus Gateways website the gateways are more expensive than the PLC (~$500) we are getting, doesn't make sense to spend more on the gateway but get a plc with the right languages to communicate with the KR C4 in the first place

    1. One of the Servo Motors on the End effector tool is designed to use the Clear Link Motor Controller or at least that's what was recommended to us from the End Effector Design Team. In the Wiring Schematic for the clear link controller, it shows a direct EtherNet/IP Line from the controller to an Allen Bradely PLC. So the PLC would Master the Motor controller, while at the same time the PLC would be the slave to the KRC4. I would have to explore this option and make sure I can use Ethernet/IP with the KR C4.


    2. We would like to program everything from Kuka's software and the teach pendant, the idea is that we spent a lot of time and money on the Kuka Arm and the software and the Training so we would like to use it as much as possible to take advantage of it. If we run into a major brick wall, will consider the reverse option

    1. yes. that device shows up as EtherentIP slave ("adapter")


    so you have three nodes: PLC, ClearLink Motion controller and KRC. all of them could be communicating via EthernetIP.


    One of the three need to be a master. Since you want PLC to be a master, you can make KRC a slave. that will make the configuration very simple. but this means purchasing correct EthernetIP option for your robot.


    2. again this is not very clear from your end. programming and controlling are two different things. you could have all your endefector gizmos programmed through PLC using whatever your PLC programming software is. but in operation, PLC can receive control signals from robot to do whatever you need your endeffector to do. robot program would simply trigger functions that are programmed in PLC. another option is to not use PLC at all. then all programming would be done on robot side.


    3. if you find gateway to be expensive ($500) then you will find that EtherentIP robot option will be even more expensive. KRC supports EtherCat too but only as master.


    4. using PLC (rather than KRC) to automate some tasks makes sense. development could be easier since completely independent of robot motion planner. plus (making online changes etc is a good plus. there are PLCs out there that support EtherCat and EthernetIP but they will also cost much more, not to mention that programing software is also likely not free. more like $1500+ just for software.


    5. the things can be done in hardware or software. using something that is already done can dramatically save time to get results. but it looks like you may have to rethink your design choices and architecture. if one is comfortable with programming, it could be enough to just use https://teknic.com/products/io-motion-controller and perhaps skip plc all together. your application could be used to implement any logic that PLC be doing and communicate to KRC using one of open source options.

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    Quote from Time3Brainstorm

    2. Its been purchased already, so its pretty concrete that I need to use EtherCAT/Profibus/DeviceNet unless I'm missing something critical from the KR C4 Manual

    Components should be bought with the correct communications options. Systems should be designed with this in mind before any purchases are made.


    Robots can have these options changed after the fact, but it's always more expensive to buy a field upgrade than to purchase the robot with the same option pre-installed from the factory.


    EIP is a bus, not a point-to-point protocol. It can support dozens, if not hundreds, of nodes on the same network. As Panic said, if all your nodes can "talk" EIP, then you simply have to decide which one will be the Scanner, and the others will have to be the Devices. A good network switch may be necessary to "split" the cables, if the number of connections you need to make exceeds the number of physical ports available.


    At the physical layer, EIP works the same as any old computer network. It's just less forgiving of network congestion, packet delays, etc. For a small network, regular home-office grade networking switches and cables should suffice. 100MBit should be fine, Gigabit would be great but probably overkill. 10Mbit... might work, but I wouldn't try it.

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