PLCMentor.com

MrPLC Member
  • Content count

    302
  • Joined

  • Last visited

Community Reputation

24 Excellent

About PLCMentor.com

  • Rank
    Sparky

Contact Methods

  • Website URL http://www.AutomationNC.com

Profile Information

  • Gender Male
  • Location Carolinas
  • Country United States

Recent Profile Visitors

3778 profile views
  1. Why (U) an OTE?

    Sorry I have to respectfully disagree on this.  There is nothing that can be done with the OTU in the situation you mention that could not be done on the rung with the OTE. 
  2. Why (U) an OTE?

    I agree that are uses for the OTU with HMI and SCADA interfaces, but there would be no need for an OTE in such a case.  In addition there should be one OTU with all the conditions grouped on that rung.  That's why OTL/OTU's can be evil!  People place them all over the program and it ends up making one giant mess.  Unfortunately he probably has one of these programs that has evolved over the years with a little here and a little there programming and no attention to the program as a whole.  Nothing like the patched patch of a patch to make your day interesting.
  3. Why (U) an OTE?

    There is no advantage to doing that.   I have seen it before and it screams poor programming practices.  Keep in mind that if you are using a PLC5 or SLC the outputs are not updated until the ladder scan is complete.  In your case, the last unlatch wins.  That can get very ugly.  If you move a rung in your program you can possibly break the program so be very careful with what you do in that program.  That said, I would be looking into the program to see how I could eliminate the OTU's if it were my program.  Keep in mind that depending on the program it could get very tricky. 
  4. DF1 and PLC5 vs SLC500

    I would think that even if the registers were different in the PLC5 versus SLC (ie swapped bytes or something), you would at least get a garbled number.  As I understand you are not getting anything.  That said, even though the cable he posted is wrong, he mentions getting online via RSLinx with autoconfig.  If he has been online with the PLC5 via his cable, then it should be correct. 
  5. studio 5000 ultilzation chalenge

    Ideally you would have some sort of SCADA system that would log downtime events and be setup with scheduled runtime for your machine.  As has been mentioned, you are basically being asked to achieve a poor mans OEE.  As you mention, keeping track of machine run versus stop time is pretty easy.  Joe mentions using the system clock to avoid issues with powering down the controller.  You may also want to add an additional variable to be stored.  Possibly a daily expected runtime number that would allow you to calculate some basic OEE number that has some meaning.  Just logging up and downtimes doesn't let you know if the machine is operating outside its expected run periods (ie, planned downtime versus unplanned downtime). 
  6. DF1 and PLC5 vs SLC500

    Are you sure your communication parameters are correct.  It looks from your text that you are sure about the cable.  The periodic comm light flashing seems to me like a comm port that is trying to connect but not achieving a good connection.  Can you connect up a PC to this port and get online just to insure the cable and comm parameters are correct?
  7. RSLogix5 Analog Scaling

    Actually Michael the SLC isn't from this century either!  LOL
  8. RSLogix5 Analog Scaling

    If you are using the PLC5 you have to scale old school.  Since both of your ranges start at 0 (raw and scaled) then it makes things a little easier.  You can scale at the card level but you lose resolution.  Just use a compute block.  The raw input from an IFE defaults to 0-4095.  0 for 4 ma and 4095 for 20ma.  Hopefully you already have the data transfer from the IFE in the program or it gets a lot harder.  The data from the IFE transfers via a Block Transfer Read (BTR).  You should be able to go into the BTR setup and see the data address associated with your input.  It will be an integer data file such as N7:0.  You can use a compute block (CPT) to do the math.  You will divide your input by 4095 and multiply the result times 50 for your new scale (N7:0/4095*50).  Your destination should go to a floating point such as F8:0.  If your block transfers are not setup then you will probably need to spend some time with the books to get that one figured out. 
  9. SLC5/05 in unmatched chassis

    Ack!  I guess I have been using micrologix controllers too much lately!  I did a quick check before my post but didn't realize that project was a micro.  Glad Mickey stepped up to cover my tracks!  (or any other appropriate word that might go there)
  10. SLC5/05 in unmatched chassis

    Just go into the I/O configuration and click on advanced config for the module that is not there (or double click on it).  You will see a check box "ignore configuration error."  Check that box and you should be able to run your program without faults.
  11. Flex I/O Rack

    Sounds like you are going in the right direction.  The flex is an older remote i/o system but it is solid and I prefer it over point I/O or remote racks.  If you use the AENT communication module then you can just drop it off of an ethernet I/P connection which is fairly straight forward.  In addition to the I/O modules, you will need compatible terminal bases such as the TB3.  Each I/O module will need to be evaluated for compatibility to the proper terminal module, but the I/O documentation is detailed about which modules pair with which terminal blocks.  I would stay away from the 32 point modules as the wiring is less straight forward.  The 16 point discrete modules and 8 point analog modules make wiring pretty intuitive.  You get 8 modules per drop so you will need to plan accordingly on that. 
  12. Clearing a bunch of counters at once

    You need to use the RES instruction just like the 5000, but you cannot put them in series.  You will have to put them on parallel branches if you want them on a single rung.    
  13. Yeah I guess part of the problem is that none of us can figure out why the logic you have shown would not do what you say you need.  If what you shown is not working then you need to take a another look at armadillo's post.  Maybe you have used the timer somewhere else in your logic?  In addition to the deadband you can also just latch in or better yet seal in your alarm output once it trips.  Reset it with an alarm acknowledge button or something.  Also your logic shown does not compare the float with 20 it compares with the value in N7:2 which is shown on your pic to be 0.
  14. So the timer does time, but the signal still bounces?  Are you saying that the signal will never be under 20% for 5 seconds due to noise or some other factor?  The logic you have shown should be timing given what you have in the pic.  Does it time if N7:0 is set to 20?  Have you tried as Armadillo mentioned jumpering around the leq instruction?  That would eliminate other issues as he mentioned if the timer starts timing.  If not then the problem is with duplicate timers or other issues he mentions. If your signal is jumping to the point that it will not stay below 20 for 5 seconds then you could use two different values for hysteresis.  Say go below 20 to start the timer and go above 25 for it to stop.  Or maybe something needs to be done to fix a noise problem?  I think we need more info on this.
  15. Set of instructions or labs for Noob?

    Kaiser, The problem I have with Rockwell's labs is that they are designed to get you in and out in an hour thus they hold your hand through the entire process.  I think that works ok for us experienced guys, but new programmers have to learn the struggle and work through creating a program without all the hand holding.  That't the biggest problem I have with all of the manufacturer's training programs.  They lead you through everything to make sure they can cover the material in the time allotted.  For me and you that's OK.  I know I am generally just looking for the new stuff that has come out when going through one of those labs.  New programmers end up being as lost at the end as they were in the beginning.  Having to program with a nudge or two is the only way I know for someone to actually learn to really program.  That's why we offer the mentoring approach.  I think most experienced programmers on here can point to at least one mentor that has helped us along the way.