Cannonier10

MrPLC Member
  • Content count

    19
  • Joined

  • Last visited

Posts posted by Cannonier10


  1. Absolutely,

    The periodic tasks in your project should be created for the respective machine function, and each function should have a priority.  Tasks that have a higher priority, interrupt lower priority tasks.  A lower number equals a higher priority; so, a priority of 1 is the highest priority task.  The only thing that interrupts a periodic task with a priority of 1 is controller overhead, safety tasks, and motion planner.  So, priority 1 tasks are your most important machine functions.  Priority 2 is the second highest...etc.

    The watchdog is the amount of time the controller waits to fault in-between executions of a periodic task.  So, when a periodic task initially executes the watchdog starts timing, if the periodic task doesn't execute again before the watchdog elapses, you will get a major or minor controller fault.  After each time the periodic task executes the watchdog resets.  This protects your controller and machine from endless loops, and helps you monitor execution time.

    You should download the Logix 5000 Design Considerations manual.  The manual number is 1756-RM094L-EN-P, and you can find it in Rockwell Literature Library.  Typically, I don't recommend reading through entire manuals like they are books, but I do recommend reading through Chapters 4 and 5 of this manual.  A lot of good information in it, that should be committed to memory by anyone who programs in Logix 5000 often.

    Hope this helps.


  2. I'll be brief...the 1734-IB8S data is created as a controller scope safety tag.  The inputs can be used anywhere in the project; they already are global datatypes.

    Also, don't use continuous tasks.  Instead, create periodic tasks and give them all the proper period, priority, and watchdog.


  3. Do you know where I can find the procedure to blow away a L7?  I already have the procedure for the L8 style, and I am familiar with removing the battery on the L6 style, but I can't find anything on the L7.  Didn't find a reset button on the PLC like the L8, and as far as I know the L7's don't have a battery like the L6's do.

    The PLC already has firmware version 33 so I guess I could try to update it to version 34.  But I guess at this point best case scenario is I can wipe it and then re flash it to version 33.

    Thanks.


  4. An overspeed fault is caused when the motors actual speed exceeds 150% of the maximum rated speed.  This 150% point is the lesser of the two between the motors rated speed or the axis maximum speed setpoint.  

    More than likely if this has been running for some time now it is possible that someone has "accidentally" lowered the maximum speed setpoint in the axis properties.

    There is also a chance that the integrator programmed a SSV to automatically change the maximum speed in a certain condition.  But that would be unusual if none of the hardware or gear ratios needed to change.

    I'll attach a couple of pictures...

    Screenshot 2021-03-30 152443.png

    Screenshot 2021-03-30 152904.png


  5. Bob,

    This was an L83E that we keep in our shop for testing.  We keep the switches set to REM, practically always.  There weren't any other PLC's or Synchlink cards in the same backplane, so I don't think this was a master slave issue.  When we swapped this L83E with an L72 we were able to get the motion group to sync right away.  I factory reset the L83E and the problem went away, motion group synced just fine.  We have used that PLC for motion applications before so we aren't real sure how CST was disabled.  I wasn't able to find much in any forums either.  Typing that term into most forums returns obscure results.  I think this is one of those problems that might not get solved unless someone from RA knows, or if someone has ran across it before.


  6. Yes you can run trends from the emulator.  You should be able to set them up in Studio the same way you would if you were using a real PLC.  I have never had an issue running trends from the emulator.  If you are having issues, you might need to reinstall RS Emulate.


  7. Has anyone else ever ran into an issue like this where the Time Sync checkbox is checked, but the CST mastership is disabled radio button is lit up?  This was causing our motion group to never sync up, even though it says that it is the Time Sync Master.  Do you know what causes it?  I was able to clear this by defauting the PLC, I just don't know what ultimately caused it.

     

     

    Screenshot 2021-03-24 110357.png


  8. It kind of sounds like you answered your own question.  I wouldn't necessarily say your are doing anything wrong, I think your testing is wrong.  If you are going to emulate the PLC it is usually better to emulate one routine at a time by exporting that into a dummy project.  Trying to emulate entire projects all at once by just changing the IO and Motion Group makes testing slow and inaccurate.  Just export the changes you made into a dummy project and verify that the code is working the way you want by creating statuses in that project.  

    I keep a L-83E on my desk if I need to test large projects and I can't break it into smaller pieces, it tends to be a paper weight though.  I should probably dust it off again.


  9. Something to keep in mind is that some devices firmware have to match the firmware in the controller.  For instance if you are using SERCOS drives, the SERCOS card's firmware has to match the firmware in the controller. 

    It sounds like this is a PLC that has probably been in place for awhile.  I would hesitate to update the firmware initially.  My first thought would be to install Studio v24 and let the PLC stay the same.  I have many versions of Studio and RSLogix installed on my machine because of this, since I know sometimes bad things happen with firmware updates.  You can download any version of Studio or RSLogix from the Rockwell website.

    If you need to update the firmware I would make sure I had the original program backed up, I would look for any firmware dependancies, and I would make sure I had a spare controller if I needed it.  Honestly that would be my backup plan though.  Should be fine, but you never know.

    Depends on your situation too...is this PLC in a machine that is spitting out product, or is it sitting on a desk somewhere.  If it's in a machine, I would leave it at v24.  If it's on your desk...well that's up too you lol.

    -Cannon


  10. Are any other switches or routers connected to this switch?  There could be duplicate IP's or the switch could be caught in a loop.

    If this is a managed switch make sure that those ports are enabled and are configured correctly.  

    Honestly ethernet communication is incredibly reliable as long as the settings are correct and cables aren't broken.  We could troubleshoot this quick if you would be willing to tell us what IP address and subnet your PC is on, as well as a list of the IP addresses that you are trying to ping.  One screenshot of the IP address that you can successfully ping as well as a screenshot of one of the IP addresses that you are unable to ping would help a lot too.

    1 person likes this

  11. On 10/15/2020 at 9:35 AM, pcmccartney1 said:

    Rockwell has a "free" download for a program called "Motion Analyzer".  It will give your the cam profile needed.  It will even write the code for your PLC.

    Any tips on how to use the software effectively.  There isn't much material out there on how to get the most out of it.


  12. I think we can add the switches.  Both options would work because I know that we use digital pressure sensors that are just mounted to a backplate, and Festo makes switches that can be installed onto the bank itself.  I guess I am leaning on trying to convince them that we need them.  Because whether the switch is outputted into Safety or not, as it stands we don't have any pressure feedback on the bank.  Maybe it isn't required for safety...but at least knowing that the bank has pressure should be required...

    1 person likes this

  13. The banks control a variety of things really...There are usually several solenoid valves on each bank, and those solenoids can control Belt tensioners, raising and lowering of anvils or conveyors, blowoffs...etc.  These individual solenoid outputs are controlled in the normal routines of the controller.  In the safety routine though, if the main bank solenoid output is closed, then we are constantly checking the input to the 1734 Safety RIO which is a pressure switch on the bank.  So if we turn air on to the bank, we are checking to make sure that enough air is present for all the individual solenoids...if not we have a safety fault.  Also, I wasn't guessing...the pressure switches ARE wired into the safety modules...

    The problem is that recently we made upgrades to the machine, and the upgrades did not contain a pressure switch...do we need them?


  14. On 8/4/2020 at 7:44 AM, Joe E. said:

    So, I wrote, and then deleted a little mini-rant about STL programming. This probably isn't the place for it...

    I will say that not all code can be converted back and forth between LAD and STL. If you write code in LAD and convert it, you will end up with a number of NOP instructions scattered around. Sometimes, you can eliminate them and have it still convert back, other times not. Also, in my experience, code written in STL wasn't divided into networks correctly to be able to convert to LAD. To convert it, I would almost always have to divide each STL network into multiple networks before it would convert. I usually could get it to convert after that, but every now and then I'd encounter one that wouldn't go from STL to LAD. In my experience, LAD would always convert to STL, but not always the other way around.

    Joe E., I would be ok with you starting a new topic to rant about STL programming.  Lol


  15. Short backstory:

    We have a machine programmed with AB that has several banks of air solenoids.  This is an older machine so the solenoid banks are of the older variety.  On each bank there is a pressure switch that is outputted into a Allen Bradley 1734 Safety RIO module.  We are adding new modules to this machine after about 10 years and the Mec Eng. chose Festo CPX banks, but they did not put pressure switches on them.

    Question:

    Is it a requirement (OSHA, OMAC, ISO...etc. any of them really) to have a pressure switch for air module?  Or are they used to just make the machine smarter?  The big concern that I have is that the customer will notice that these new CPX's don't have pressure switches to monitor the status of the air like every other bank on the machine, then questions will be asked...yatta yatta...


  16. What is the best software/application to use for editing cam profiles in Studio/RSLogix?  I have a machine with 4 knife blades on a rotating load.  These blades would need to be cammed to a conveyor based on size of the current products recipe.  I know the diameter of the load, and gearing, but I am not sure how to calculate my cam points.  Thanks.