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Found 3 results

  1. Continuous sine wave problem

    Hi,  I encountered specific problem during work with PLC&HMI application. The main task of that system is controlling torque changes of induction motor with inverter&analog PLC output. There are few built-in functions to change torque: exponential, constant, trapeze and unlucky sine. All functions are implemented as array of 1500 values. When array reaches 1499 element, it comes back on first position and so on. It works without any problem for exp, constant, trapeze and sine wave with natural numbers of frequency e.g. 1Hz, 3Hz etc. The trouble appears when we want to control torque with float value of frequency and unfortunately its the most important part of that project. When the float value frequency is chosen, the last element of array is totally different than the first one. In result, in every period of array, appears drop of value. Check the attachments to comprehend what's going on. The first image shows GXWorks restriction of index. The second image shows how does it look on simulate screen, where it's representation of PLC registers D2000 - D3499. On third and fourth images you see values of registers in Device Memory Batch of GXWorks. Fifth image shows the script which I work on. Do you have any ideas how to implement float values of frequency in correct way? I should make an opportunity to online change of sine frequency in continuous way between 0 and 10 Hz, with 0.2Hz step. I will be very grateful for any advice.  Greetings, J
  2. CJ1M-CPU23 Reading a square wave

    Hello, I have a flowmeter (macnaught flowmeter) which says that it outputs a 2 square waves. I am unsure how to connect the flowmeter to my plc (CJ1M-CPU23), do I need an additional unit or can I use the general purpose IO things mentions in the manual (IN6-9 say they are high speed counters)? Any advice would be appreciated. Thanks, Jay
  3. I see there are some nice math instructions in the NJ's menu.    I can't use a MC_MoveAbsolute.  It must be a Cosine position curve running from zero to a positive max end position. I imagine I can use an offset to start the curve at zero, as the COS instructions produce a wave from -1 to +1 and back again.   The trick is to start the curve at -1 and end it at +1 ... If you know an easy way to do that, please share..     Regards, Michael   PS:   This may seem silly .. but, after finding it so easy programming a Delta Motion RMC75E motion controller to due exactly what I'm asking above... I am surprised as to the degree of difficulty dealing with Sysmac & the NJ ...  The level of complication is excessive, if one tries to go beyond the available Function Blocks, Functions and packaged math expressions.    Sure it's easy to do a trapezoidal move from one position to another.  But, I want a cosine curve (or, if you like, a sine curve) .. they are somewhat the same ... but not exactly the same .. and they are certainly not a trapezoidal move component.       I know The NJ can do sine waves ... Check this out: Perhaps, this video will help illustrate the problem.  Regrettably, it may require some innovative programming on a complex level ... such work is often done for the programmer by other manufactures of Motion Control modules...  it is certainly beyond my experience, and ability.  Any suggestions, short of actually writing the program, would be a big help in my learning curve... Thanks much.