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Posts posted by drforsythe

  1. I tried to find some info but could not locate manuals.  If you have a model number, it would be helpful.  I believe these devices are timers with multiple outputs.  In the case of this one, it looks like it has 30 possible outputs and your system has 25 of those outputs wired.  As the drum turns, the outputs turn on as the "flags" placed on the drum reach the actuation point (one spot along the drum where the individual switches are placed).  This looks like an industrial version of a vacation timer for lights in a home to make it look like people are in the house.  To convert this to a PLC, you will need to have or develop a wiring schematic that identifies which switches on the device control what devices on your equipment.  Once you have that, you should be able to draw another diagram that identifies the relationship of each switch flag to each other, which will be time-based.  If the unit still works and my assumptions are correct, it would be helpful to know how long it takes the drum to rotate one complete revolution.  If you know that, you could determine the duration of each of the switches "on" time based on the number of degrees the "flags" cover.  From there you could code your PLC based on the relationships you find with your diagrams.  I would be really interested in seeing a schematic for your system if you have one.  Good luck.  That is definitely an interesting piece of early automation.  A "keeper" for a collector, for sure!  Good luck in your conversion.  Please update this post with your findings.  

    After re-reading this, I see you had the model number there the whole time, in plain sight!  Sorry about that.

  2. I know you stated they were wired into the safety modules.  That was not the question.  I was just wondering why you think they are wired into safety modules.  If the air pressure is critical to safety, that is why.  If it is just critical to machine operation, then a normal input module would suffice.  Let's not let that trip us up, though.  I am not aware of any regulation that requires you to have a safety switch on each bank.  I could be wrong, though and if someone know differently, please share because I like to learn.  Only you and the machine designers can determine if anything is needed.  If you want to maintain consistency with the rest of the machine, could you just add pressure switches to the input air lines to the new Festo valve banks?  That would allow you to keep the Festo valve banks and still maintain the same standard that was set on the original part of the machine.  I don't think it is necessary for the switch to be integral to the valve bank.

  3. It would be helpful to know if this is a new application that you are just starting or if it is for a machine that has been running normally and this is a new fault.

    Excessive position error can come from many sources, including bad feedback device or cable, excessive load, stuck brake (if equipped), electrical noise, improper tuning, inertial mismatch, etc.

    Does this happen when in motion or sitting still?

    If in motion, how long does it take for the fault to occur after motion is commanded?

    If it happens while sitting still, does the motor have any audible noise or vibration you can feel?  If so, check your tuning.


  4. It is not a requirement that I am aware of unless maybe you are in a specialized industry.  What do the pneumatic banks control?  It makes me wonder why the pressure switches are wired into a "1734 Safety RIO module".  What happens when a pressure switch is not made?  Does it cause the safety system to shut down all or part of the machine?  Or possibly lock a gate closed?  If the pneumatic system controls vertical cylinders and air pressure is required to hold the cylinders up, it could cause a safety concern if pressure is lost.  Without more info, I can only guess.  Give us an idea of what the pneumatic banks control and why you think the pressure switches are wired into safety modules.

    Aside from all of that, I do like air pressure switches on my machines.  I typically only do it on the main air supply to the machine, though.  I do not put them at every valve bank.

  5. The only manuals I know of are the Mitsubishi manuals.  Based on your question and the device you mentioned, I will guess that you are asking about the TO and FROM instructions.  If that is the case, I will do my best to explain it.  It has been a while and I am doing this mostly from memory.  The info below is generic and not specific to the FX2N-4DA.  I do not have  a manual for that handy. 

    Analog cards and other special function modules need to be set up then read from across the backplane of the PLC.  This is not an automatic function and is accomplished by using TO and FROM.  Whenever we want to send something to the card, we use TO and whenever we want to read from it, we need to use FROM.  The instructions work this way:

              TO or FROM  [module number] [head address number] [data to read or write] [number of words or devices to read/write]

    Module number:  In plain English, if you have a special modules in your rack, they start with 0 and number all the way to 7 in the FX platform.  The first one is 0, the next to the right is 1, then 2, etc.  This number can be a decimal constant (k) or hexadecimal constant (h)

    Head address number:  This is the register in the module that you are reading from or writing to.  This number can be a decimal constant (k) or hexadecimal constant (h)

    Data to read or write:  This is the info you are sending to or reading from the head address number in the module.  This can be a constant (h or k) or it can be a memory location in the PLC (i.e. D100)

    Number of words or devices to read/write:  This is a constant (h or k) that tells the controller how many items to read or write.


    Hopefully I got this right and didn't confuse you more.

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  6. Check for reads and writes using ANY input or output.  What I mean by that is, do a search for X0 and see if there are any reads associated with it.  They may have programmed it to read in whole words of inputs at a time and write that to an internal word (D0, for instance).  Post the program and rack layout if you are allowed.  I currently do not have the software installed, but depending on the format, may be able to get it installed.  Regarding the PC boards, it is possible they are converting the signals from DC to AC or PNP to NPN?  If you have prints, post them as well (if you are allowed).

  7. A lot of people program that way.  I think the intent is to go back to put some "default" values in but they often don't go back to finish that step.  

    On another note- I used to work for a distributor of Mitsubishi.  I would commonly run into the problem where someone had uploaded their programs using Medoc to create their backups.  For small, simple machines this would work fine.  For PLCs that were programmed using the GPP units, we would often run into a problem where whole sections of machinery would not work.  The problem was that the GPPs had tables that could be filled out to configure their remote I/O networks.  Medoc did not have these tables, so when the program was uploaded, that data would not get uploaded.  Therefore, when the program was downloaded again, the remote I/O would not work.  For users of Medoc, the TO/FROM instructions needed to be added to the program in order to configure the network.  In this case, people thought they were doing the right thing and because of a large gap in functionality between Medoc and the GPPs, they would get hosed.

  8. The circuit shown is a solenoid locking safety switch.  The arrow inside the circle denotes a positive break contact as IO_Rack stated.  The symbol is used to show that a device has contacts that are mechanically linked so that if they weld, the contacts will open when the actuator opens. (At least that is what is supposed to happen.)  This is most likely a gate switch that will show "closed and locked" when the gate is closed and the solenoid is on, which locks the gate or door shut.

  9. This is one of those topics where people are going to answer 'absolutely' based on their experience.  There is potential for high emotions and lots of cheerleading for or against certain manufacturers.  I will provide my viewpoint without really endorsing any one brand.  I have used all three brands.

    STRENGTHS - consider cost, availability of product and support personnel.  In my opinion, two of the three have decent software and one has always lagged.  All three offer world-class hardware and capabilities.

    WEAKNESSES - The biggest potential weaknesses from my viewpoint are cost and support with software a close third.  Geography has a lot to do with the support.  The best support for Mitsubishi is going to be in Asia, the best support for Siemens is going to be Europe and the best support for Allen Bradley is going to be North America.  (Don't get offended if you offer great support for one of those companies outside of the areas listed.  It is a general rule, not an absolute for EVERYONE who supports the products.)  Two of the above companies are GENERALLY more expensive than the other.  Two of the companies generally have better software than the third.  The company that doesn't have the best software has generally made up for that by making a nearly seamless upgrade path as hardware becomes obsolete.  The other two are quite as easy.  You figure it out.  

    OPPORTUNITIES - This is highly dependent on the industry being served.  Each of the three have their core industries that they serve and that is highly dependent on the location of the industry.  All three are in the steel industry and automotive industries, for example.  The main thing that has determined which of those companies are selected in those industries starts with location and the available inventory, support and software.  

    THREATS - Again, geography can come to play with all of these companies.  All of them have inventory in all major areas, but not all inventory. These three companies have huge presence in the world, but they don't have everything everywhere.  I have had issues with Mitsubishi and Siemens with lead times on replacement parts because I am in the metro Detroit area.  I have not typically had this issue with Allen Bradley.  I would think the same situation happens with any of the manufacturers if you are trying to source something away from any their "home" continent.

    I have purposely not answered your question specifically because there are so many variables.  Strenths, weaknesses, opportunities and threats are all dependent on the individual or company making the analysis as it relates to their particular situation and needs.  Each manufacturer provides claims that their product is easiest to use, has the fastest processor, the broadest instruction set, the most robust hardware.  They are all partially right because each one has their own unique measure of their claims that do not consider what the competitors claim.  Sorry to muddy the water.  All three companies make great products that can control most any process.  All three have broad offerings that all integrated within their families.

    I look forward to the responses to see how each fairs on a SWOT analysis.


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  10. Most of the time when I have seen these levels of current needed, it is for hydraulic control.  In those cases, the manufacturers provide the driver device and allow a voltage (-10 to +10v, 0-5v, 0-10v), current (0 to 20 or 4-20mA) or potentiometer input.  

    Is the Hawe directional valve drive motor an electric, hydraulic or pneumatic motor?

  11. It looks like you gave the part number for the mounting bracket for mounting a FLOW meter to a pipe.  Keyence makes a flow meter that does not require breaking into the pipe, but the bracket must be properly sized.  They have a flow meter that is ethernet/IP-capable that also accepts a PRESSURE switch input (a separate sensor) for sending flow and pressure.  Please clarify what exactly you have.

  12. I would be interested to know the model and manufacturer of the flow meter.  It is not unusual for 4-20mA devices to transmit outside of the 4-20mA boundaries if there is a problem with the sensor.  This is built-in to some models so your controller can tell if there is a problem with the sensor.  On some ultrasonic distance sensors we once used, you could select if the signal would go less than 4mA or higher than 20mA if the sensor failed its diagnostics.

  13. It is quite common for the utility companies to change the power delivered based on demand or power factor.  If you are in an area where you and your neighbors are using a lot of power during the daytime, but not so much at night, the power company will compensate for that.  The other thing that could be happening is that a plant in your area may have a new piece of equipment that is affecting your plant.  The best thing is to get a power analysis done for at least a week and including at least one weekend.  With the proper test reports, you could identify if the power is surging or sagging and if there is a harmonic component present.  The report would also show you times of the occurrences which will help you and the utility determine the cause of the issues.  Your report should include voltage, current, harmonic and power factor.  You can conduct these tests at the main source to your plant or in discrete locations, depending on the size of your plant or where the problems are.

  14. As ControlsGirl stated, we will need to know the hardware to start.  Is there a PLC, or is the HMI connected directly to the stepper motor drives?  Please provide the info below:

    Manufacturer and model numbers for the PLC (if any), stepper motor drives, HMI.  Also, please describe the interconnection of these devices (serial, ethernet, DeviceNet, Profinet, digital I/O, etc.)

    Also, how are the commands sent to the stepper drives?  There could be several ways, such as direct (serial) commands from the hmi, pulses from a PLC, or index location via network or digital I/O command.

    Depending on the type of drive you have for the stepper motors, it could be fairly easy.  The more info you give on this forum, the better responses you will receive from the contributors.



  15. We use Micro Motion flow meters throughout our plant.  They are great meters.  We have had issues with the old (>20 years old) devices after power failures.  I don't recall which model the old ones are, but we cannot even get them repaired reliably.  We have been systematically replacing the old units with the 5700 series transmitters.  They work with some of the old flow sensors, depending on the number of wires in the sensor.  I highly recommend contacting Emerson to find out who your local Micro Motion salesperson is.  They are really good to work with (at least in my experience).

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  16. Unloaded motors are difficult to tune and will sometimes exhibit the problems you describe.  If I were you, I would try one of the following:

    Find a load for the motor.  It could be a plain gearbox with no load, or a pulley system.  It is best if you can create a geared ratio of at least 3:1.  The higher the ratio, the better results you will find when doing the autotune.

    If you can't find a load, then try to change the autotune parameters relating to the motion.  I am not near the software, so I can't tell you specifically what to change.  Start with the distance then change speed.  I have a feeling once you open up these settings, you may see a failure in the autotune.  Again, unloaded motors are hard to tune and that may show up if you try it with a longer move or higher speed.

  17. When you say that the hookup test ran flawlessly ("The motor will slowly turn... for as many revolutions as I input.")  Are you using the same speed settings (accel, velocity and decel) settings when you run your test as the hookup test uses?  I have had similar experiences during my testing where I have had aggressive accel or decel rates or the speed was excessive.  

    How long after motion starts do you receive the error?

    Do you have any gearing between the motor and the load?  Is the inertia of the load within the motor specifications?  If inertia is not matched between load and motor, then you will be able to achieve slow velocity movements but will most likely fail when positioning.


  18. Google translation:


    Direct Scripting Script


    Is it possible that someone can help me, in FactotyTalk, I created a script that le excel spreadsheet data, but this by clicking on a button. How do I make this script run right behind my screen without having to click the button ???

  19. What RPI setting do you have set up?  If you try to communicate faster than the camera can respond, you will drop connections.  The info may be dated, but I found a reference that the RPI should be no less than 10mS with a Cognex camera.  Please post the solution when you find it.

  20. We have been using Strongarm enclosures in places where we need to suspend them from a wall or pole.  They offer painted and stainless steel enclosures. They have several options available.  the website is www.strongarm.com.  Good luck.

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  21. I find myself getting frustrated with vague or overly-simplified requests for help, as well.  Sometimes I think that it would be awesome to have a forum with a form to fill out that asks for pertinent details, then makes those details searchable and filtered by manufacturer, model, symptoms or scope.  I am sure there are some knowledgebase and web-based support forums for products that are like that.  Then I realize the following:

    1)  It takes time and effort to create a support forum like that.

    2)  If that support forum were created, we would all find things that would be nice to have for it.  Once we added our 'two cents' to the list, the wants list would become too large and searches would either return way too much info or not enough.

    3) Those that do provide pertinent information when asking for help will find the required information for the forum to be a juvenile requirement and then probably not use the forum anymore.  This would lead to a reduction of requests and more importantly, a reduction of responses because of the extra time it may take.

    4)  Then, the most important one - freewill plus the GIGO principle.  If someone does not provide adequate information (Garbage In) or is simply looking to get their homework done by someone else, we all have the free will to choose not to respond to the request (Garbage In = Garbage Out).  OR, if we have time to help,  we could simply post back the info we need in order to help.