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I had to upgrade the control system of the plastic extruder. V700 + V200-18-E46B used in application. The system has been operating successfully for over 2 years. However, a separate installed dosing system that determines the color of the plastic has failed. It has a stepper motor, a driver and a failed control board. I quickly connected the input of the motor driver to the output of the O0 npn PWM and programmed the change of the PWM frequency depending on the speed of the screw of the extruder. Everything worked, but there was one problem. Sometimes the stepper motor must be stopped for a few seconds without stopping the extruder (for cleaning). Accordingly, the stepper motor that started smoothly with the extruder to a certain speed must stop and then accelerate again. And here I find a problem - the output of the PWM which perfectly controls the stepper motor when starting from 0 speed does not want to start smoothly from another source. That is, the variable recorded as the PWM frequency changes smoothly to the setpoint - but the PWM output signal to the stepper motor occurs only after 2-3 seconds and with a frequency that has already reached the required value - respectively, the motor does not start because the frequency is too high. This part of net is controlled by START STOP STEPPER MOTOR BIT. I try to use it for accelerate stepper motor after stop and if it is slower then calculated frequency setpoint ML6. ML11 - PWM frequency, MI61 - frequency change step. I do not know why PWM signal output is paused for a few seconds (i try to disable all other net for test). If MI61=1 - pause is approx 5sec after ML11 reached setpoint, if MI61 = 50 - pause is shorter 1-2sec. If i use MI=200 - pause is short but stepper motor do not start sometimes. I try to see PWM frequency in Info Mode - it is changed correctly but PWM output do not start after PWM frequency variable start to increment. Any ideas for stepper motor start stop controlled via V200-18-E46B PWM output frequency? -
Hi Team As a rule I try not to preset values at power-up so the PLC will retain it's state after a power fail. This is particularly useful when I'm running timed or timer functions which just pick up where they left off after a power glitch. Sometimes I use SB 2 when I do need to reset stuff after power up. Now the real question - Is there a way of detecting when a new programme has been downloaded? I have been trying to use SB75 to detect when a new ladder has been loaded; that's when I definitely want to do a full reset of values to known states. As my very first action in Main I've tried testing the bit being Set, Negative Transition, Positive Transition and for each case I've SET an MB (which has a power-up reset state). Nothing seems to move that MB. So I'm wondering, does SB75 actually go high in first scan and drop at end of scan? Maybe I'm misunderstanding what SB75 is for. Is there perhaps a better way to know I have a new ladder downloaded to the PLC? I possibly could have a current-version MI and a last-version MI and make sure I change the current-version power-up value to check for version change but that's a little mes Oh also, I'm using a V1210. Many thanks for any guidance coming my way cheers Mal