John_R

This is a PT100 input, which is based on a resistance measurement principle where 0-degrees C = 100 ohm, and changes about .4 ohms per degree. so it would seem that 1-320 ohm is basically the range of a PT100 sensor. So if you ever have the need to precisely read a resistance in a project, there you have it....... JohnR

Yeah Aus, I have some programs that use the Transfer >PLC>PC or Transfer> PC>PLC, and it does make more sense..... Now, A-B uses the Download to PLC and Upload from PLC contention, so it must be correct........? JohnR

I find this terminology perfectly acceptable..... You have to look at it from the point of which device is the larger resource. Yes, when you are connected to your network and/or the internet, you are downloading information TO your computer and uploading FROM your computer. But, in the case of connecting that little PLC to your computer, the computer is the larger resource, as it contains all the information that you need to download TO the PLC, and if you are sucking a program out of a PLC, then you are uploading FROM the PLC Just my 2 cents.......

Hey All, often times, when I copy a .vlp file from my desktop to my USB thumb drive I get the following warning; I then copy the vlp. from the USB drive to my laptop or another PC I never have a problem with the program when opened, Just curious what "properties" this is referring to...... JohnR

Flex, In my case it's not so much how it was saved, but rather a result of something I've done....... If I have a project open that I'm working on, saved as serial connection, then a some point I change the comms to I/P and go online with a different PLC and use Remote Access to look at something (and that's the caveat, you can do that because Unitronics doesn't compare the online to offline), then I go offline and back to my project, and then later forget I changed comms...... Ooops...... It's an "old-timers" thing, forgetfulness......... :-) JohnR

I've burned myself on this this kid of "fun" more than once...... I'll be working on a project at my desk, and do a download intended for the serial connection to the project on the bench (and having forgot that I was online via I/P to a machine out in the plant earlier in the day), I inadvertently send the download to a running machine causing an interruption on the plant floor....... A little quick thinking when I realize what happened, make a quick download of the correct program back into the machine and get it back running..... Make embarrassing apologies to those who understand by blunder, and tell those who don't that the machine just "glitched"........ All in a days work, :-) JohnR

+1 on Joe's thoughts, I have a V570 project I did a couple years ago, and was kicking around the idea of going to a V700, but I will have to resize graphics on every display..... JohnR

Hi Gonzalo, I follow what you are trying to do, and appreciate the fact that you do have a true safety circuit, but I would still be concerned that by not using the safety circuit when making adjustments you could be putting the user in harms way.... I don't pretend to know exactly what you are controlling, or what hazards are present, but please be mindful of the users surroundings and what could happen........ Is there any stored energy (air, hyd, water), that you need to release before entering the area? If you are going to pursue this, I would at least make the "MCR" a keyed switch (and one that the key can't be removed in the Run position), and the user must have possession of the key while making adjustments. Regards, JohnR

Now, we also do not know what the OP's reason is for wanting to do this, but my first guess is that he wants to create a "safety" of sorts, isolate the outputs so the user can perhaps make adjustments to a machine without shutting down. Now we have to bear in mind that just because the outputs are turned off, the program itself is still running, and any inputs that can change the state of the logic, WILL! And when the outputs are turned back on, the machine may not be in the same state it was. SURPRISE! So, now we could take that same "MCR" contact and inhibit inputs so the program sits still where it was..... And that gets us to the old saying; "JUST BECAUSE YOU CAN, DOESN'T MEAN YOU SHOULD" If this is indeed a pseudo-safety circuit, then we have opened up another can of worms. At least here in the US, a safety circuit is not part of the running program, but instead a separate mechanical (usually redundant) safety relay that takes power away from the PLC's I/O. And that leads to a whole different conversation........ JohnR

Flex.... you are correct if you were to just put a contact in series with the output. my suggestion is to replace the outputs with MB's, set/reset, toggle, or any latching contacts are now done in the logic with the MB that MB then controls the physical output, with the inhibit/start/stop/MCR/whatever-you-want-to-call-it contact before the physical output. JohnR

Or you could replace the output coils with MB coils, then map the MB coils to the associated output coils, then make an MB that you set for your stop condition, and put an inverted contact for that MB before each output you want off. JohnR

Now, I'm certainly not saying that I religiously follow these suggested guidelines from the book. As I said, I usually design/build things the way I see them, and show the users what's going on, some get it, some don't. As Aus said; "I have realised over the years that there are definitely humans that don't have natural intuition at following anything computerish. Carefully step them through a process until they've got it, and a week later they can't do it again, even though everything is on screen clearly displaying what to do" But, I do appreciate the pretense of the book. As the programmers, we all know well what a given control really does in the big scheme of things, but giving the user a defined control that makes sense to how he thinks the process works is what makes a good user interface. And I imagine getting to this point would be easier with a whole design team dealing with every step from conception to finished product, gathering user input and all kinds of thoughts of how it should operate........ But, when you are a one man band, trying to bang out something usable against a deadline, you don't always think about how the user will perceive it...... Flex- Interesting what a little joke dredges up...... JohnR

I've used a lot of V280's over the years, they use to come with the battery installed, and not accessible without opening the unit up, but a couple years they changed the case design and included a battery compartment cover with the battery stored in a plastic bag within, and a sticker on the side reminding you to install the battery JohnR

Like many others in this field, I am the "controls guy" in a manufacturing plant, and I am often the "Judge, Jury, and Executioner" when it comes to building controls for some new process. Sometimes it is hard to predict how the end users will take to a design, there are things that seem simple and obvious to me, and completely baffle the user. I have a third edition copy of About Face, this is an excerpt from the first chapter that kind of sums up the goals of the designer/builder. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Goal-Directed Design is a powerful tool for answering the most important questions that crop up during the definition and design of a digital product: Who are my users? What are my users trying to accomplish? How do my users think about what they’re trying to accomplish? What kind of experiences do my users find appealing and rewarding? How should my product behave? What form should my product take? How will users interact with my product? How can my product’s functions be most effectively organized? How will my product introduce itself to first-time users? How can my product put an understandable, appealing, and controllable face on technology? How can my product deal with problems that users encounter? How will my product help infrequent and inexperienced users understand how to accomplish their goals? How can my product provide sufficient depth and power for expert users? ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Things that make you go Hmmm........ Regards, JohnR

well, a week since I cleared my log files and it's still running.............. odd the the "run time error" description does not lead you that direction.... stranger things have happened, just you wait and see.......

Thanks for the input Cam, I'll look at that tomorrow and see if it helps. BTW, back at work after 3 months of sitting on my behind.......... JohnR

Bump........ Creators? Anyone? JohnR

Hey All, I know this is an old thread, and the OP has come up with a solution, but just wanted to share for future reference......... A couple years back I had a machine setup with an M91 in an awkward location, and I went through many plc's, not only through physical abuse, but also direct spray from high pressure water washdown damaging the keypad, after buying unit after unit, Joe T (my distributor), was able to get me replacement keypads so I could take the unit apart, peel off the old keypad and apply a new one, much more cost effective in a chronic damage location. I don't recall the part number offhand ....... Joe T, care to interject? JohnR

Hey All, I've been out of our plant for a few months recovering from some surgery, but I do log into a PC I use about once a week. This PC is running two instances of DataExport, each collecting data daily from two different control systems, and I typically just let them run in the backround. I have been running it like this for a few years, but lately one of these has been dropping out and popping up a window showing "Run-time error 3709", "The connection cannot be used to preform this operation. It is either closed or invalid in this context." Has anyone out there seen this before, or know what the error is trying to tell me? Regards, JohnR

Well, I use to comment my code in the first person; "In this net "I" store the raw encoder count from MI 1 to MI 12, then "I" scale it for use on the display....." But, over the years I've come to commenting in the third person; "In this net "We" store the raw encoder count from MI 1 to MI 12, then "We" scale it for use on the display....." It make the PLC feel like he is really part of the process......

Screen/Shield, always been the same thing in my mind, although from a broader perspective, shielding may refer to the braid/foil/drain wire on a cable, while screening may be thought of as something in a bigger sense, like a metal (screen) partition between noisy parts of a panel and noise sensitive parts..... I've been doing industrial control for 30 years, and was always lead to believe "one end" grounding to be proper in this field. But, before that, I worked in the audio electronics field, and the proper method was to ground both ends of the shield, but you also did your best to maintain a "star ground" topology to eliminate potential ground loops..... just my 2cents..... Disclaimer.... at least in my part of the world, I realize Aus and others have words and meanings that us funny tawkers don't get........ JohnR

Hi Cam, Good call....... Silly old me, I have a RHR to get the fault code from the VFD right below MI 13, and the vector length was set to 16..... DUH....... JohnR

Hey All, Just ran across a quirky little thing while working on a new project, I'm wondering if anyone else has experienced this..... I'm doing MODBUS control of an AB Powerflex VFD , and mind you this is not my first experience doing this, I've done several projects using V570's, and usually do not run into problems. This time I'm building some controls around a V120, and I am having an issue reading the speed feedback (frequency) from the VFD. I've compared my logic to a previous project (logic looks the same, only difference is the MI's used in the RHR FB), and even set up two PLC's on my workbench (V570 & V120), and hooked up each to the same VFD to test. Problem I have is that when the net is true, I get the correct reading, but when the net is not true I get some other number in MI 13. I have searched MI 13 and it shows it only being used in the RHR FB and on the display. I have slowed down my index to 1 Sec per step so I can see it in debug, and find that if I unplug my MODBUS cable while The net is true, then MI 13 stays put even after the net goes false, so it doesn't seem that the funny number is being driven by something in the program. V570 reading speed feedback of 60Hz V120 reading speed feedback of 30Hz when the index equals in that net V120 reading something else when the index does not equal in that net I'm starting to wonder if it has something to do with Enhanced Vision vs. Standard Vision? Any thoughts? Regards, JohnR