drforsythe

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Posts posted by drforsythe


  1. I have had difficulties with motion instructions when moving from one processor and FW level and going to another.  I cannot recall the details of the FW level but I think it was 18 to 21.  I would suggest making a copy of your file, then opening that copy in Logix 5000.  Then open the controller properties and change the controller type and FW level.  Once the conversion is complete, you will be able to see if all of the code converted.   If you see 0 errors once the conversion is complete, you should be good.  IF USING MOTION commands, you may still have issues, but you will have to cautiously determine how you will validate the conversion.  On our system, it was obvious.  We couldn't run until we changed some code.  If I remember correctly, it just had to do with timing one of the commands.


  2. If you have double checked your settings and tried the loopback test with no luck, the port is probably gone, as you suspect.  I am not aware of a better test to try.  The loopback test is the base test I always start with.  If that doesn't work, there is usually a physical port issue.

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  3. Can you post images with notations on them that show what you are inspecting?  A good/pass image and a bad/fail image would also be helpful.  From there, we can look at the images to help solve your problem.  At my facility, we have solved a lot of our lighting issues by using infrared lighting and filters.  This way, ambient light conditions have little to no effect on the process (unless you are directly under a window where the sun rises or sets).

     


  4. There is an important detail that we must all know in order to begin helping:  Is this a new problem on an existing system, or are you just commissioning the unit for the first time?  If it is an existing system and the problem just started, you should look at what could have changed in the mechanical system (such as a loose or damaged coupling, or a change in payload or a program change that modified the speed or acceleration / deceleration).  If you are starting this system up for the first time, then the tuning parameters will need to be changed.  It has been a while since I used Mitsubishi servo drives, but I seem to remember an auto-tuning setting that described the rigidity of the system.  If you have this setting too high, but have a compliant mechanical system, then the motor will make noise at the beginning or end of each move.


  5. The L298N is an integrated circuit, so a lot of us on this site are not going to be familiar with their use.  If possible, it is best to attach a specification sheet to help us help you.  A quick search shows that the L298N is a device that takes TTL inputs and drives inductive loads such as solenoids, relays and stepper motors.  That being said, the Q Series has output cards that produce TTL levels.  The manuals are available online.


  6. Crossbow, that is not the way I understand it.  I was taught that G codes typically deal with the motion control aspect of a CNC and M codes deal with the canned functions like turning the coolant on and off or turning a spindle on and off.  I am not a CNC expert, but the motion controllers I have used operated this way.  A quick Google search confirmed this.  Maybe it is device specific?


  7. Hello All:

    Our plants are going through some expansion and the forecasts for more business are looking quite nice.  I have been tasked with determining where we stand in regards to available electrical power, chilled water capacity and compressed air availability.  For now, I am going to concentrate on the electrical aspect, but maybe there is a device that could cover all three.  I am looking to monitor the three phase voltage, power, frequency and calculate power factor on at least eight (8) main transformers.  I may decide to monitor to the bus level at a later date.  I would like a system with an OPC server that can serve this data to our OSI PI data collection system. 

    Regarding the chilled water system, I have four (4) systems to monitor. I would simply monitor set point (which may be manually set), outgoing water flow and temperature and return water flow and temperature.

    I have two air compressor systems to monitor.  For that, I would simply need pressure.

    I could always connect the sensors for the chilled water and compressor into a PLC and then connect our OPC server to that device, but for the electrical power, I would like something off the shelf.  Ideally, if I could have one device do all three, that would simplify things.

    If you have any experience with a device that would work, please share.  

     

    Thank you in advance.


  8. I will offer this advice:  When designing controls, picture yourself in the position of the operator(s) of the equipment you design.  Try to think of all the ways that the process could fail, then design hardware and software that can help mitigate those issues.  If you work for a company that will allow it, spend some time working as an operator of the equipment you will be designing/programming/improving.  Build empathy for the daily users of the equipment.  If you can understand what it is like to be a daily operator of a machine or system, you can then make it friendlier to use.  Also, use your ears more than your mouth.  Listen to suggestions from those around you.  Being humble will earn you more friends than being cocky and thinking you know it all.  We all want to think that we are the best designers with the every detail thought out.  It is easy to get trapped in the pit thinking that our way of thought is the only, best way.  The truth is that people who regularly use the equipment know a lot and have valuable info to share.  By developing empathy for the users and including them in your design process, you will earn their respect and have allies when it comes to solving any problems that might creep up.  Classes are helpful, but not as helpful as fully immersing yourself into the situation.  If I had to suggest one class, it would have to do with communications.  Not the communications that deal with networks and devices, but interpersonal communications.  Learn how to communicate with the varying types of people you will deal with.  Sorry for the long-winded post.  Best of luck!

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  9. You mentioned that it only made 300 parts.  Unless the output cycles several (hundred) times per part, it sounds like the load requirements do not match the output capabilities, as others have said.  If the inrush is too high for the plc output, place a socketed relay between the plc output and the load.  This way, if the relay fails, it is easily replaced and much less expensive than the plc.  Plus, then no work would have to be done on the plc (changing output addresses or downloading program to new controller).  If you still wish to drive the load directly from the plc and it is inductive, put an appropriate snubber on the output, as others have said.


  10. You should be able to completely clear it by removing the ROM, unplugging the backup battery (if installed) and removing power from the unit for at least 30 minutes.  It has been a while since I regularly supported Mitsubishi products, but their RAM seemed to be backed up for a long time using a capacitor circuit that allowed change out of the battery without losing the RAM.  Even though you have a ROM module, the program is loaded into RAM upon power-up.


  11. Wow.  I haven't heard of that processor in MANY years!  One thing to think about:  Do you know what the plc was originally programmed with?  The dedicated programming units (GPP?) also known as the "big orange programmer", were widely used before the prices of PCs came down.  When I first got into this business, they were still quite popular - especially with the automotive plants.  The GPPs were able to access parameters that Medoc was not able to.  The biggest parameter set I had problems with were the MELSECNET/MINI parameters.  If a machine was programmed with a GPP and then someone used MEDOC to upload and download, the MELSECNET/MINI devices would no longer work.  The only way to get them to work was to add TO/FROM lines in the logic to set up the network.  The TO/FROM logic replaced the tabular settings available in the GPP.

    All that said, if the machine was set up originally with a GPP, there could be a parameter that Medoc cannot access and therefore give you a mismatch.


  12. You should also explain what your goals are in monitoring these systems.  As kaiser_will added, comm options are important.  Some additional questions to ponder:

    - Do you want to archive the data, or just see the processes while they run?

    - Do you need to display alarm conditions?

    - Will you be using this as a monitor-only function, or will information pass from the control room to the processors?

    - Do you require some intelligence to predict how your processes will respond in the future?

    - Will you be programming from this control room?  If so, what firmware is in your CPUs? (This is important to know what OS you will use and if you need to have VMs installed to manage multiple rev levels of the programming software)

    - Will you need to be notified automatically via text message or email if an alarm occurs?

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  13. Steve:

    Ha ha!  Obviously, I did not notice that.  I saw the recent replies and went along for the ride. 

    I didn't translate John Carvajal's message until you posted the age issue.  For anyone interested, an online translator offered this translation of his post: "It may be dust or moisture on the bus's chassis, please download the drive and blowing the backplane. Once the drives not passing 2 and became a cleaning and now everything is ok".

    Well, maybe it can help someone in the future...


  14. You sent me info stating that you are using the IL 100 with a 1768-L43 CompactLogix and were asking about an EDS file.  First, the IL 100 is just the sensor from what I see on the Keyence website.  It looks like there is an amplifier that should go with it, an IL1000.  When I looked at the info for that module, it looks like it has standard digital outputs for pass/fail and an analog output for measurement.  I do not see a network option that would require an EDS file.  What is your plan for interfacing the sensor to the PLC?  I am not an expert in this particular sensor, but these are the things I see.

     


  15. It would be helpful to know which Keyence laser (and controller) as well as the PLC manufacturer and type.  Don't forget to tell us how the plc will get the values from the laser (analog signal or communication network).  It might be helpful to explain a little about your application.  There is a lot of experience on this forum, but we need details in order to provide the best help.


  16. I agree with PLCMentor- we need to know exactly what is "tripping".  Is it the whole cabinet or just the plc?  If the problem is intermittent, it may require you to monitor several things with a meter that can record the values against time.  Is your PLC powered by AC or DC power?  I would monitor the incoming power, any DC power supplies and try to relate that to what is happening in the process when the fault occurs.  If your main power is staying up, but your DC supply is dipping, then it could be related to a load that is putting your power supply into a current limiting protection mode.  If your AC power is not consistent, try to relate when the fault occurs to the time of day.  Are other machines having the same problem?  Does the fault occur at the same time(s) daily?  If so, it could have to do with how your neighbors are using the power or it could also be the power company inserting or removing correction capacitors to manage the power factor.


  17. It depends on the equipment that is doing the control.  You need to look at the individual pieces and determine the manufacturer and model before the software can be determined.  Are these machines already built?  If so, then what is the manufacturer of the controller, drives and human machine interface (if any)?  RSLogix500 is the software used for Allen Bradley's SLC and Micrologix programmable logic controllers.  I also don't understand something:  you mention two motors, but three variable frequency drives.  I have seen multiple motors controlled by a single drive, but not vice versa.