Post by mubeta on Strange problem with the ‘MC_SetPosition’ function ^{CODESYS Forge talk (Post)}
How are the servo drives controlled? EtherCAT, step/dir pulses, other? CANOpen, 1 Mb/s, bus load 35%, cycle time 2ms. Another thought is that - if it's step/dir pulse based control - the pulses from the PLC to the drive are getting missed/lost at high frequencies? If that's the case then there would be multiple troubleshooting steps/corrections that could be investigated. Here, it seems to me that we are getting completely off track with the observed problem. You could try to create a simplified program I had already written this elsewhere. The program before being brought into machines was exhaustively tested in SW emulation and the problem did not occur. However, in emulation I was interested in checking other aspects of the process, not this specific one which is for real a correction made necessary after the fact. The part of the program that does this correction with the function mentioned in the topic, came up from its origins, but I didn't know or didn't think it was really useful. A scruple that later turned out to be necessary. However, for now I do not think I will spend any more time on this verification, already lacking any to do my normal. I remain amazed, however, that a function intended to correct the axis position with the motor in motion and that it should not interfere with this, in fact instead changes behavior as the motor speed changes. Mah! When you manually control the motor directly from the servo drive software at the speeds you are calling for, does it move precisely to the target position? The drive and motor have been working fine for about 10 years. In replacing the machine control system, I opted for CoDeSys where before there was something else. But this is not the subject of the problem. What I need to resolve is the fact that a clutch specially placed at a certain point can slip and, therefore, I have the undeniable need to phase the 'prime mover' to the mechanical position of the machine, detected by a cam for each turn, in order to properly stop at its optimum point. Which for now I have ruled out doing. In fact, if I really have to say, since we have now gone brutally OT, I originally thought that this clutch should only come into action in cases of extreme necessity, as happens in most trials. But this one, the way it is made, slips more easily than I could estimate and the servo-controlled 'prime mover,' and the machine, get out of phase, maybe by a little, but frequently, and when the machine work at it's high speed, (in fact all of the time), I can't adjust properly the 'prime mover' position at fly.
Last updated: 2025-01-18

Sort by relevance or date