JimRowell

Chris, The problem I have with pass-through mode on the E terminals only rears its head if I do longish comms between a pc and the plc through the terminal. For instance in a recent project, I have a pc program running on the customers pc which allows him to send and receive complex recipes to the plc. The recipe features in the E-terminal are not used. If I connect the pc to the hmi, I can do minor pass-thru such as monitoring points in the plc from the pc. On the other hand, a recipe transfer will sometimes lock it up and requires a power cycle to restore the hmi. I've had the same thing happen on program transfers from Medoc too. It seems to be a matter of how long the comm lasts. If I connect both the hmi and the pc direct to the plc, there are no problems. Jim Rowell

Sergei, I agree with you 100%. Actually, 110%. As I said in my post, I'd use your suggestion of MOV myself. I was simply mentioning the BON method as an alternative more out of interest than anything else. It could prove useful in the odd situation such as if you were stuck with a section of memory where you couldn't spare 4 bits. I admit that's about as likely as world peace, or me retiring before the next millenium. I suspect that Mitsubishi's designers intended the BON instruction to be the one used in this situation (otherwise why even put it in) but MOV is just as effective and much faster. And as you mention, it works on all models. Jim Rowell

How fast do you need to accel and decel? What will the top speed of rotation be? How much torque is this "significant torque" that will occasionally be transferred to the inner cylinder? If you can handle gentle movements, without knowing all the details, it sounds like something that could be done with a standard ac motor with brake, gearbox and inverter drive. For position feedback, a simple encoder setup would do it. 1/2 degree is not too hard to achieve. I've done a few setups with 1/10th degree positioning using some pretty rough components. Jim Rowell

Another way is to use the BON (bit on) instruction. Example: (This will check 100 bits starting at M0) LD M8000 RST Z ;initialize Z index to 0. FOR K100 ;number of bits to check. LD M8000 BON K1M0Z M100 K0 ;current bit being checked is moved into M100. INC Z LD M100 ;Do whatever you wish if M0 plus index is true. LDI M100 ;Do whatever you wish if M0 plus index is false. NEXT The advantage is that only 1 destination bit is affected rather than the 4 used by Sergei's method. The disadvantage is that BON is slowwwww.... Personally, I'd opt for Sergei's MOV suggestion. Jim Rowell

I find it's best to use the 232-BD board. It's very low cost. I use it even with E-terminals. I got tired of having problems with the pass-through mode on the terminals and find the BD board to be a very good solution. I connect the terminal to the programming port and the PC to the BD board using a standard cable. This also means less wear and tear on my sc09 cable since it stays in storage. I just noticed that you are referring to the 'C' version so the above will not help you. I don't think the fx2nc can use the BD. That being the case, I guess I second the idea of using an E-term and the pass-through mode.

The definition of Sink/Source gets a lot of people in trouble. The trouble is that the original confusion-free definition as defined by the electronics industry has been improperly used by some of the plc manufacturers such as Mitsubishi. The following quotes are from my article Industrial Control Safety: Definition of Source/Sink: Example: Let's say you have a relay with the negative side of the coil connected directly to the negative of your power supply. Then you have a switch which connects the positive side of the supply to the positive side of the relay coil. That switch is going to supply positive charges to the relay coil when you turn the switch on. That makes the switch a "sourcing" device because it is a "source" of positive charges as far as the relay is concerned. The relay coil is a "sinking" device because it accepts or "sinks" the positive charges from the switch. If you instead connected the positive side of the coil directly to the supply and switched the negative line to the coil, then the coil would be a source and the switch would be a sink. Jim Rowell

This would have been better posted in the Lounge since it's not really an AB issue but here goes anyway... Panic, For a description of OEE see... http://www.productionprocess.com/screens/i_oee.html >Are you a freelance programmer ? yes. >If so do you supply (with the program): >· Process descriptions Usually. Depends on the budget and the project. >· Flow charts I would if I was asked... I've never been asked. I'm not a fan of flow charts. I prefer p-code. >· I/O Lists Always. >· Test results Never. I do extensive testing and then deliver a tested product. Testing is a dynamic process and attempting to show test "results" to me seems somewhat contrived. >· Do you write OEE friendly programs ? Often. Depends on the requirements. >Do you have / use an I/O protocol ? I use whatever protocol suits the project. >Are you a programmer employed by in the manufacturing environment ? Yes. >Does your industry have programming methodologies ? I suppose. >If so what are they ? I've no idea. I don't worry about it. I write my programs. The industry uses them. So... why are you doing this research? Jim Rowell

I should probably add a point or 2 to my previous post before someone gets in trouble. Typically, transformers supply a mix of motors but that's not always the case (especially in an automation application). If you have a transformer where the majority of the load is a single motor (or multiple motors that are started together) and you are using full voltage, across-the-line starting then you may want to consider the voltage drop caused by the starting current when sizing the transformer. Voltage drop will affect the motor's starting time. Excessive drop can make the starts very slow or even prevent the motor from reaching speed. It's not likely to be a problem if you size the transformer at say 70% or less of its rating. The secret is knowing the starting current and the impedance of the transformer. The "percent impedance" rating of a transformer as stamped on the nameplate is defined as the percent of the total circuit impedance that exists inside the transformer when at 100% full load. In other words, in a 5% transformer, at full load, 5% of the total circuit impedance will be inside the transformer while the other 95% will be in the load and the wiring. This also translates to a 5% voltage drop at the transformer's terminals when at full load. If you size this transformer at 100% of a motor's running current and that motor has a 500% starting current, you would see a 25% voltage drop during the startup (500% or 5 times the normal 5%). If you sized it at 50%, you'd only see a 12.5% drop on startup (much better). I'm not sure how reliable such a linear assumption always is but it seems to pretty much hold true in my experience. Bear in mind that these drops are in addition to any created by wiring. And of course, as the motor comes up to speed, the current falls and the voltage drop decreases. Motors generally have a startup current of about 4 times the running current. The typically stated range is 4 to 6 times with 5 times being the accepted value for use in calculations. In real life, most motors are closer to 4 times. For transformers, 5% impedance is very common with a few being 3%. Since you normally would want to size a transformer at 30 to 70% of its full rating anyway, you would not go too far wrong even with a single large motor as the load. But as you can see from the above, staying closer to 50% or less would be way better for single motor transformers. It's an important point for those (such as me) who might otherwise load transformers quite high and then rely on external cooling to prolong their life. I like external cooling via fans. A force-cooled transformer will run at a very low temperature even when loaded above 80%. Unfortunately, this cooling does not help in the voltage drop department. Jim Rowell

Well, the original poster stated that the primary was 240 volt and the secondary was to be 120 volts. That would generally indicate that we are talking about single phase. As for inrush, you don't need to consider that for most setups. Exceptions to this would be if you are doing a lot of continual motor starting or if you have motors that are exceptionally slow to start but neither is all that common. You should oversize your transformers such that they run very cool for long life anyway. Just like breakers and fuses, when properly sized for the running load, the normal inrush encountered on startups can be completely ignored. Control transformers are slightly different in that they often feed high inrush loads as well as loads that are very sensitive to voltage drops. That's why one would typically use a separate transformer for control that is rated as a "control" transformer. These have very low impedance values so the output voltage varies less as the load changes. Anyway, you are right that 3 phase is different. For 3 phase, VA is the voltage times the amperage times the square root of 3 (or 1.73). KVA is VA divided by 1000. Jim Rowell

An engineer needs a lot more than a basic knowledge of math. He needs a thorough grounding in it when he is starting out. Then when he settles down into his chosen area he may or may not need to continue with it. 90% of engineers use very little of it. Or rather they use an important but small part of what they learned. As for not bothering to search, that's pretty insulting. I'm sure the engineers I asked could have found the info had they had the time and interest. On the other hand, I know many, many PC software developers and few of them have more than very basic math skills. They get help there when they need it. As for me, I'm not an engineer. I don't have a good grounding in math. Nontheless, I've managed to perform some very interesting projects. Engineers don't necessarily make the best integrators or programmers. I do have a good grounding in programming and electrical theory. And I have many years of experience in the fields of general electrical and automation. I wish I knew more math. It's important but let's be realistic. Anything beyond basic trig or arithmetic is a very tiny part of what most of us do. I respect those who have different specific points of expertise. A little less bravado and a little more effort on your part would go a long way torward us all learning a little more. Jim Rowell

I know what you mean but on the other hand, I've heard a lot of stories about the "unscheduled break schedule" too. Actually I've seen a few of them myself. You know, the fuse that magically vibrates out of place (the one that takes 2 hands to push back in), the wire that just pops off, etc. One of my first service calls to a certain printer was to remove paper from behind a fuse. Are you sure there wasn't the odd titter going on? A not so straight face? Some of the dumbest characters I've known could make a machine do things that I could only dream of despite the fact that I designed the controls. Maybe not so dumb after all.

You could also have a look at these files describing the different kinds of parallel ports (read about the standard port first). I zipped them into one for you. par_port.zip

I have no idea who Paul is. That's not a good thing considering that I wrote it. I meant to say Gerry. Gerry, Paul... they do sound alike, no? Or how about, in my family, we call everyone Paul just to avoid confusion. Or Paul is short for Gerry? Okay, maybe I've been working a little too hard. (I can't wait to put my current project to bed).

I just tried it and it worked fine. Perhaps they were doing some maintenance while you were there. Try again. You need to register in order to access the downloads section of their site but the general sections of it are open access. Jim Rowell

You need to give us a little more info. How do you use the PC program you have now? Do you just run it? Do you need to go through various menus? Can you run it from a command line with parameters that tell it what to do? Do you have any sort of programming background such as Visual Basic? If the program in question can be controlled via the command line then you could have the PLC send commands serially to the PC. You could then write a simple application in the PC which would be listening for the serial comand from the PLC. It would then start up your real PC application with the appropriate parameters. For instance in Delphi you can start up another application by executing the following Windows call: ShellExecute(Handle,'open', 'c:\windows\notepad.exe','c:\SomeText.txt', nil, SW_SHOWNORMAL); The example starts up NotePad and passes a parameter that tells it to open a file called 'SomeText.txt'. It could just as easily have started up your test program and passed it parameters indicating what to do (instead of the file name). VB and other languages have their own similar methods. You may be able to run the dll's directly too. DDE is another option. You need to know just what your existing application can and can't do. Jim Rowell

I'm not familiar with what you are using but you should double check your communication settings. It's possible to have pseudo-successful communication with certain incorrect combinations of baud rate, data bits, etc. It shouldn't happen if your software and hmi are checking the data properly but not everything does. It's worth being extra sure that your setttings are correct before pulling your hair out looking elsewhere. Jim Rowell

You can get a demo copy of 2004 Electrical for free simply by requesting the CD. Go to www.autodesk.com and fill out the form. It comes with a good tutorial that will get you started. For programming, you can go to www.meau.com and download the programming manual for any of the Mitsubishi plcs. If you are not sure what model then start with the FX2N. You can also try my tutorial here at mrPlc. It has a slant torward the FX series. Find it here. Also have a look through the forums. There's a lot of good stuff buried in there. If you have any specific questions, feel free to ask right here. Someone's bound to have an answer! Jim Rowell

That's correct unless the BL1800 is different then any others I've seen. The situation is no different than it is with a plc. You have to provide some external method for user interaction such as a PC or a self-contained HMI display (or lights & buttons or whatever). You could consider some of the low-end lcd displays. Some of those even have built-in buttons or allow connection of cheap keypads. Connection to the sbc is serial or usb. You can be up and running for between $70 to 200.00 (plus the sbc, enclosure, etc). Try MatrixOrbital. The Jackrabbit is very respected although I'm not personally familiar with it. All sbc's come with at least one if not several serial ports, pwm, ADC, DAC, etc, etc. Fairly complete packages. Usually they have exceptional support software including debugging facilities that far surpass anything you'll find in a plc. On the other hand, because of the sophistication of some of the systems, you need all the help you can get. If you want low price and a very good setup for beginners, you could check out the Pic stuff. It's not very sophisticated but it's used in a lot of consumer products and is fairly capable. Has a simple instruction set. Fast and cheap. There are many sbc's based on it. The most well known for Pics is Pallalax. Their boards are smaller than credit cards. You could also try BasicMicro. Jim Rowell

An SBC is just a compact computer. No keyboard. No monitor. No drives. It's usually not an IBM compatible although that's quickly changing. Most of them are built around the Intel 8051 processor or competitive derivitives but there are lots of other popular ones too like the Rabbit (Z80), Hitachi and 6500 stuff. Usually 8-bit or 16-bit. There are now quite a few that are built with 486 or pentium chips. Basically if you add I/o modules and an operating system to it, and put it in a box, you have a PLC. Most are programmed using C. Some have an on-board BASIC available. Some have their own control oriented language. Some people program them directly in Assembler. They come with a host of features built in but the available I/O is usually logic level and requires interfacing to use. Many OEM's use them rather than PLC's since they can be very affordable especially in quantity, very compact and offer very high performance. They are usually not a ready-to-go solution like PLC's are nor are they always as robust as PLC's (but they can be). Jim Rowell

Thankyou Jacekd. That was the kind of answer I was hoping for. A quick net search failed to yield that (maybe too quick). I'll do some compares of the Taylor series and the aproximation thing and see what happens. As for the engineers, I guess it's like anything. Use it or lose it. Everyone forgets what they don't use and many engineers (many, many, many) don't really go into it out of true interest. The four I asked don't come under that category. They are very good at what they do but I've could write a book about some of the others. Examples: "That shiny thing is one of those leds, right?" or "Hey, I'm doing my basement so can you show me how to wire a 3-way switch?" or "Okay, we have 10 coolers at 15 amps each... so we should run a 3/0 down the line and tie em all into that, right?" or "Yes, it's a N.O. switch but I'm showing it closed on the drawing because the boom is hitting the switch when the machine is in the rest position so I need to draw it as Normally Closed, right?" or the latest one "We don't want to run another channel all the way from the E-Stop. Can't we just put a safety relay in the cabinet ahead of the contactor?". I've got a million of em. Jim Rowell

Paul makes good points and that's why I originally mentioned about talking with your reps. It depends on so many things. 1/2 second is not much time if you are having to reach a high speed. I didn't realize you wanted to go from dead stop to fast in that 1/2 second figure. Your figure of 223 doesn't seem too high but how much can you expect from a regular motor and drive in that short a period of time?. I don't know much about flying shears but I would imagine that in at least some cases (maybe?), you can perform the cut while moving past the target without actually matching speed exactly. If the cut is short and the material is thin and pushable and doing that doesn't disturb the material feed. I was envisioning an oscillating punch press type of affair (the only style of flying shear I've seen). In this setup, you don't have to start from zero nor do you ever accelerate very far nor do you ever reverse direction. You merely have to correct for changes, delays, etc in the system. I did a quick google on flying shears just now and the back-and-forth style ones seem to be the rule. They're using either linear motors or servos combined with dedicated controllers. They seem to be quite concerned with the overall inertia of the system since it's a very high demand type of system. Has to be very accurate and has very high accel rates. I'd be a little too concerned to just fly (shear or otherwise) by the seat of my pants if I were you. Jim Rowell

No. A small local box and display manufacturer/packager. Not sure about the exact number of employees. At least 40 skilled including office plus maybe 20 unskilled/temporary. Basically a healthy, competative company whose market demands flexability and fast turnaround. Iso is a bit too restrictive in their opinion.

Just as an aside... I know of one company that went iso quite a while ago and goes through all of the usual painful documentation procedures with one exception. They pretty much ignore iso on the plant floor except for appearances. They've found that inspection consists of a rigorous viewing of records and written procedures in the office followed by a brief and shallow (inexpert might be a better word) inspection of the plant. It means that they implement the PM and other good ideas of iso requirements but don't get too hung up on anything they disagree with. It has basically been a good thing in that it has convinced them to actually do the things they think make sense (but might have had a hard time finding the money for without the iso excuse). Anything they think is counter-productive, they simply ignore. I'm not suggesting they are doing the right thing but, at least in their case, a small company can find wiggle room if it really wants to. Of course it could lead to a problem should inspections suddenly get more rigourous (like loss of certification).

I'd go with the 37kw if I were you. With the 30 you'd have to worry more about ambient temperature, cooling around the inverter, duty cycle, heavy demand, etc. Even sudden failure of the motor is more likely to damage the invertor if it's closely matched rather oversized a bit. What if down the road, someone changes the motor and the new one is slightly less efficient. I'm still a little fuzzy on what the actual nominal Euro voltage is (when measured with a real-life meter) since they standardized on 400 volt. Is the supply now 400? or is it still 380? or what? Why are 380 volt motors still being sold? Anyway, if the nominal is really 400 and you are using a 380 rated motor then your real current will be higher than the nameplate. If this is true then it's one more reason not to match the invertor too closely. Jim Rowell

Sheesh! Talk about being led astray!!! :*-( When I could not get it to compute on my calculator with more than a single argument, I asked 4 different engineers about it. Three of them had no clue whatsoever (blank stares). The fourth indicated that you had to perform it differently when using multiple arguments but he could not remember the details. At that point, I posted here for help. I wish I'd first tried my next step which was to simply use a different calculator! Now it works no problem at all. With or without multiple arguments and with or without even using the exp function itself!!! So what was the problem? The friggin #$%! calculator was faulty. Examples: 2+2 = 4; 2+2.6 = 4.6; 2+2.5 = overflow. Whoever heard of a calculator being wrong? Is nothing sacred? I feel violated. <grin> Anyway, sorry for the confusion & thanks to Lobotomi for the file. For those who want to use the equation without having access to the exp function, it's basically 2.718282 raised to the power of the argument. Piece of cake. Jim Rowell