FX3U performance for temp control

[twitte 0]

Hello, I am looking at the FX3U PLC and wanted to get some feedback on your experiences with the PID function. Specifically how many loops can be run simultaneously? How are the Mitsubishi temperature input cards? I had some bad experiences with another PLC in which the RTD and TC cards were severely affected by external noise coming from a VFD. Is there any type of input filter on these input cards? Thanks for any feedback. Tyson

[Dippy 0]

In my own experience, I've found the biggest brain ache with all these PLC PID functions is the lack of AutoTune. Having never tried the FX3U, I cant comment on its autotune function. Also when creating loop control from PLC PID functions, its only the basic core control. You still have to create other associated functions like High/Low cutbacks, Ramps, Holdback, etc.. You feel that you're re-inventing the wheel. Also a majority of the time, the finish product is used by operators/service engineers and not us programmers. So to tell them to set up the PID means timing the time when over/under shoot occurs from setpoint and then applying a little calculation to it and then inputing that value to the PID parameters is a non starter. I've tried various Loop controls over the years, from Function created loops, FX2N-2LC to descreet Modules. It all depends on the type of control you are applying to. From single to multiple loops, I now use descreet hardware modules. Not wanting to sound like an advert for this manufacturer, I'll only link their page. RKC They are off the shelf items with CCLink and very simple to use. Excellent Autotune. This is my own opinion, but in my experience, everyone wants a single button to press and after a few minutes later, All pid loops are controlling to setpoint.

[Duffanator 1]

I have just recently used a Q-series temperature control module to control 3 PID loops and I was quite impressed with how well it works as well as how easy it was to program (if you use the configurator there is almost no programing needed). I'm not sure if the modules for the FX3U are similar, I've never used them, but if they are then I would recommend them. Even the autotune works well with those temperature control modules. It does require some programing to use the autotune function but it's not very much and the manual explains it pretty well.