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denise01

Modbus Speed Control Problem

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Hello, I use a CJ1M 13 to control five Altivar 312 Inverters via PMCR easy Modbus. This is the second machine I have put this on to the first works fine after a few teething problems but my current attempt is getting some strange results. Four of the Inverters power down when an operater enters the machine, When the Inverters are restarted two of the Inverters revert to LSP that is set on their respective controls. The other two Inverters run normally at the speed as directed by the Modbus. I use a NS5 HMI which controls the Up/Down Speed. I am not getting any SLF Faults which is Loss Of Serial Connection and all the Inverters start okay but the speeds are not as directed by the Write Memory areas. Would it be worth posting the programme so somebody could take a look. Modbus is still a complicated way of doing things to me although the fact that you can control the speed via a HMI Screen makes it appealing. Regards Peter

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I can only assume you will need to resend the speed to the drive if it's noted a stop. Or you can compare the set speed versus HMI set speed before the drive restarts. Not sure of your control schema, but it's doable. John

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Modbus is not that complicated, if you think it is then why not use conventional IO. You could still set the speed from your HMI that way. I think your problem is that your altivars are not all set up the same. If you are using the same code for modbus that we worked on last time, & it works on the other machine, it won't be the code.! I am not too familiar with the ATV312, but think they are similar to the others, so can you copy the parameters to te HMI & download to the oes that don't perform the same?

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Actually, it cod be that the speed value is only sent on data change. I think the easy modbus of is configured to do that by default, but can be changed to always write. What documentation do you have for setting the easy modbus up? I not at PC so cannot check, if PMCR is snooping he may comment as well..

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Hello Lost Control, I have been through the settings on the Altivars and they all look the same to me. I have a feeling that I am sending the Speed Reference before the Inverter has had time to go through its start up checks. Once the Drives are running if I increase or decrease a signed value to the Memory area then the Speeds correct themselves as directed by the Speed Reference. I am at work Sunday so will pit in Delay Timers in order for the Drives to start and after a period of time the Speed Reference will be sent. Hope that works Regards

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Lost Control I used PMCRs Easy Modbus to set up

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Peter, Try changing the speed reference by a value of 1 up/down every 5/10 seconds, to see if that solves it. The Easy modbus code only writes the speed reference on value change, so it likely that the value is not written when the drive powers up, as it would not of changed. if you change it every 5-10 sec, then it will always try & write it.

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Okay Thanks Lost Control. I will do that but as you say why when the Code is working on another line with the same settings does it behave so strangely. I am even doubting things like Polarity wiring on SCU 31 I have Pin 1 as - which goes to D0 on Altivar and Pin 2 + which goes to D1 on Altivar. The SCU Card settigs are okay ie 19200 8,N,1 and Protocol Macro and I transfered the Protocol Macro uploaded from the good running line. I am contemplating rewriting the Read, Write Sections but once again am only using DM5000 onwards for Read and DM6000 onwards for Write so I dont see how they could become corrupted. Maybe the best way is to do one Drive at a time. Anyway thanks for your suggestion. Regards

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Hello Lost Control, I managed to get four of the five Drives running with consistent speeds byputting fairly large time delays in the Speed reference Line(LFRD). I will consult Altivar to ask whether or not their Drives Power Up/Down times have changed and whether or not you can alter the timings at all. My Operaters will not appreciate the delay before the various motors start. Not sure how to go about adjusting speed reference every 10 seconds. Do you mean add one without carry on a timer and then subtract one on a timer. Regards

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Your problem has nothing to do with the altivar settings, if what you are telling us about them all having the same setup. The way the EasyModbus function works for DataWrite is that it only writes on a change, since at startup your values are the same the EasyModbus is not seeing a change! Simply have a timer that adds 1 every 10sec, the subtracts 1. This only needs to happen at startup, but won't make any difference if it is always done. There is another way, but I don't have your code so can't be sure. Send it to me & I'll have a look. If you need an example, let me know.

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Hello Lost Control. I have sent the programme plus a Protocol Scan to your old email address. It may have changed, if so I will resubmit. Many Thanks Peter

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Hello Lost Control. Here is the Programme. The relevant section is VSD Start/Stop and the Read Writte sections that preceed it. I am still having problems with Node 2 Curler stopping when I press stop for Nodes 1,3,4 and 5. Everything seems okay in ETAD Memory Area although the Curler Drive goes to nst. Must be some way that Modbus sees all five Drives. Any examples of improvements would be much appreciated. Regards Peter 6_Lids_new_panel_260214_modbus8.cxp

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