RIzu (Customer) asked a question.
I'm looking for some help to control a system for an unwind and rewind speed control using DL-06.
I have a simple enough machine setup with the unwind and rewind motors being powered with GS1 and GS2 ac drives respectively (that I bought from Automation Direct) and I have a dancer with a potentiometer to control rewind diameter and rewind motor speed.
I am using the unwind motor as a Master (Independent) and the rewind motor as a slave (follows the Master and the dancer). The dancer input signal goes to the Analog module F0-04AD-2 from Automation Direct as an input.
Can anybody help me how to approach this? I seem to have put the pieces together, but not been able to come up with something solid.
Also, I would really appreciate any help with the programming in this regard. I went through the Automation Direct Manual for dl06 and F0-04AD-2, but had no luck.
Thank you.
I would use a potentiometer as the setpoint (SP) Use the dancer as the process variable(PV) & use PID to control it. i'm not sure the DL-06 has PID capability though. I do know that the Do-More BRX does have PID capability.
Sorry I'm late on this. I got the chance to get back on this project at work.
The Dancer has a potentiometer at the back that sends input signal to the PLC to control the spooler speed (rewind). The dancer is basically in the middle of the unwind and rewind. i can control the capstan(unwind) but rewind has to be controlled through the dancer (potentiometer).
Somewhere it seems I read you can do 4 or 8 pid's with DL-06, I think maybe it said 4 pid's for DL-05 and 8 for the DL-06, maybe experts can verify that, sound like a fun project. Good luck
+1 AkaHammer
Chapter 8: PID Loop Operation - DL06 Manual
• Up to 8 PID loops, individual programmable sample rates
• Manual, Automatic and Cascade loop operation modes
• Two types of bumpless transfer available
• Full-featured alarms
• Ramp/soak generator with up to 16 segments
• Auto Tuning
Here is a video showing the PID in action
https://www.automationdirect.com/videos/video?videoToPlay=dCca5kxVxEE
Regards,
Garry
I assume you already have the DL-06? My only experience with the DL-06 was is a very minor edit to a program someone else wrote, and my employer only has a licence for DirectSoft 32 which I think is quite out of date so I can't help you with programing. Personally I'd probably use a Do-More BRX, or possibly a P1AM-100 but if you already have the 06 and software I suppose you might want to stick with it. BTW, if one was starting from scratch, for a one off project, the price of DirectSoft compared to the free Do-More Designer could easily make up for the higher price of a BRX compared to a DL-06, but if one is doing multiple projects then the calculation changes, though one still needs to consider the value of one's time, I suspect the Do-More may have an advantage there. If one is developing once but deploying many units then hardware price is probably most important.
It is not clear what your actual mechanical layout is, it sounds like you want rewind to track unwind, using the dancer to compensate for reel diameter changes. I'd think one might want to use some degree of feed forward. Depending on the exact configuration of the dancer, it is possible a simple proportional control might work. With proportional only the dancer position will change, but given sufficient travel and a relatively constant spring rate that may not be problem and could make programing/tuning easier
I have built maybe exactly this & several variations... (40 years experience). Film control.. A lot depends on speed & weight of moving parts. More weight or speed is a 2x (or more) multiplier of complexity. If system will have small variables it's simpler. I've done simplest as a pot with simple math driving vfd. Vfd in constant torque(try variable too). As dancer (for slack takeup not roll diameter) moves more out of position the math to drive vfd gets higher (multiply by 1.2, 1.4, 2, 4). Takes experimenting. If system is fast or heavy machine, pid will probably be required. I frequently use vfd rated motors w external cooling fans. This is because I use variable torque on the "tension" or follower motor. I don't use master slave but use program to control vfds. IE tension motor runs very slightly lower Hz than master thus creating drag to keep film tight. Dancer arms are required 98% of the time (in between take up & supply drives/film) because its way way simpler than programming such tight control but it can be done without dancer takeup. With the follower motor in VT (variable torque) mode you can experiment with different torque levels to keep film taught. The follower motor will have "slip" if you understand term. The motor is like a variable brake in that mode. That's why I use external fans (on most systems) because the motor is slightly breaking all the time thus heat. Also have to be carfull about reverse emf or reverse voltage to vfd which could trip "high bus voltage". Once again electrical complexity comes with weight & speed...
Hi,
"Takes experimenting. If system is fast or heavy machine, pid will probably be required"
Thank you for your reply. System isn't heavy and what would you consider fast? We're usually running the drawing machine at 600 rpm max.
How should I wire the dancer to the tension or follower motor VFD? Do you know where to look for a simple program and wiring for this? I'm new at this so a little help would be appreciated.
Use the POT to control the payoff. As you said the Master. For the takeup, use a PID loop. Bring the dancer arm position into the PLC and supply this number to the PID PV (Processes Variable) input. The PID SP (setpoint) will be the voltage the dancer arm outputs when the dancer is in the middle position where you want the dancer to be at when running. The output of the PID will control the winder motor either voltage out or RS485. A little thought on PLC logic is needed when to place the PID in auto and to stop the takeup if the web breaks etc. Use P and I only on the PID, no D is needed. In fact D will make it un stable. A PID will control this perfectly. First time programing PIDs are not for the weak hearted but once you get the hang they are a great tool.
Thank you for your reply.
Sorry I'm late on this. I just got the chance to get back on this project at work.
The dancer is a potentiometer. How do I check the voltage on the dancer (potentiometer) when it is in the middle position to input it as a SP value? I'm connecting the potentiometer (dancer) as an input to the plc.