Jump to content

Walkerok

MVP 2015
  • Content Count

    261
  • Joined

  • Last visited

  • Days Won

    27

Everything posted by Walkerok

  1. This is an older question but I thought I would respond. Having written mixer programs before this is the method I used to arrive at the correct weight for each batch run. At the beginning of the day the mixer was zeroed. But after that never again. In my process each batch had a recipe of water, gypsum and sand. At the beginning of each batch all that is needed is to look at whatever the mixer has as its weight at the beginning of the batch and look for the difference in weight as the ingredients are being added. A screen shot of a main viewing screen has been attached as an example. In the program you just use the weights as they are at the beginning of each step as the zero point. Keith
  2. It is not possible for anyone to help with your question without knowing what the mechanical components are and how they work. Just an example question ......................... what pumps the fluid? Depending on the answer you have remarkable different solutions to the problem. Just an assumption but a vending machine that needs to meter out a fluid generally will be using a "systolic pump" so for each rotation of the pump a fixed quantity of fluid is dispensed, but non one can guess how fast the rotations will be or how much the pump dispenses in volume per rotation. You have to be much more specific in what you are using and what you are doing. good luck Keith
  3. Sorry, but there are no U90 compatible products that allow multiple serial ports (none that I could find). The original hardware you are using the JZ20-R31 does not have any analog output capability by the way, but to get the IO you need with the communications you need will take you to the V130-33-TA24 and then add either the V100-17-RS4 or the V100-17-RS4X. Thanks Keith
  4. If you go into information mode for the PLC you can get into system settings and go into the system section you should be able to make a PLC change from run to stop or the other way around. However I have never encountered a program where the act of running the program stopped the PC communications, however first time for everything. If you stop the PLC and are able to communicate then the program is what caused your problem. Good Luck Keith
  5. There is nothing pre-built into the PID function block to give you this ability but you can write it for yourself easy enough. You decide when you want to run a PID loop in your ladder. You can suspend a PID whenever your current value is within a dead band you hardcode in the ladder around a set point, or make it settable on a screen. (there is a pause I and D calculations block that will stop calculations for as long as you say. You can stop the entire PID loop when you are within the dead band for a period of time. Your choices as a programmer. Good Luck Keith
  6. So I am sure that some of you may know factoid 2 already but I decided I would share the benefit of lots of testing with everyone. In our products we use the V570, V350 and the JAZZ units to talk to variable speed drives on a regular basis. Most drives come standard with 485 Modbus as the only communications type unless you spend extra money getting optional com cards for the VFD. Two factoids relative to noise. There was a conversation that happened accidentally in the "I have a new project" topic where someone said that Unitronics was very susceptible to noise. Well VFDs make a large amount of noise and it is not always radio noise. A fair amount of the time the noise is actually contained on the local earth to where if you ground the shield of shielded cable you make your noise problem much much worse than in you do not ground your shield. The old conversation about sometimes you have to ground a shield on one end or the other or not at all must be practiced regularly. Factoid 1: I generally would not recommend one brand of product over another but 20 years of use on pressure transducers have shown conclusively that there are definite brands of transducers that work dramatically better than others in noisy conditions. If the noise is radio noise pretty much every transducer is as good as any other. If the noise is carried on the local earth ground of the machinery then really bad things happen on every brand of transducer I have ever used (list to follow) except 1. We have used: Ashcroft Murphy Pepperl & Fuchs GEM WIKA AST Dwyer (all private labeled so there is one that works) and in 100% of the cases when there is a site that has noise infecting the ground because of VFD usage there is a horrible amount of noise created (it has nothing to do with Unitronics) and there is only one cure (separate the sensor from the metal pipe is it screwed into to isolate the sensor from the grounded pipe. If you ever have a site that has what appears to have an incurable noise issue and a VFD is involved unground the sensor and see what happens (pressure sensor just unscrew it and leave is unconnected to anything metal and if your noise issue goes away your grounded piece of equipment is causing your noise issue. So what is the one sensor that seems to be impervious to noise on the grounded pipe? It is specific to exactly one model and one product type only. The SETRA 209 series pressure sensor works perfectly where nothing else will (without lots of noise smoothing). AST is second best (but not as good as the 209 series SETRA) and everything else is just bad. Unfortunately, the 209 series is not NEMA 4 rated and is only suitable to outdoor use with the help of a cover to make a 3R cover. No other model of SETRA transducer works like the 209. Just as a note (if you are not needing Class 1 Division 2) there are companies that make electrically isolated pipe union fittings (for cathodic protection) and we have used these from time to time to help customers through ground noise problems. Factoid 2: It is in the Unitronics documentation but who reads everything (or remembers it over enough time). When connecting to RS485 it is not just important but absolutely imperative that you do not connect wires to pins 2,3,4 and 5. Even if the opposite end is connected to nothing at all (except 1 and 6). What testing has shown is that if any of the other 4 wires touch each other (because you cut them short) they will make an otherwise quite communication line unbelievably noisy. Also even if the ends are not touching the wires themselves act as little antennas and noise becomes worse. How do we know and not guess at this? Because sometimes we try to do what is right and it ends up being horribly wrong. One of our techs went out an sourced a high speed modem cable (shielded with shield all the way up to a metal sheath on the plug). It was not an inexpensive cable and sounded like a really good choice. We were buying 15 foot cables and then cutting this in half to make 2 cables (other devices have screw terminals for their connections and not an RJ12 (RJ12 for RS485 to get all 6 connections) so we would cut away all cables except the two making connection to 1 and 6 at the Unitronics port. We had 70 or so with these cables out and a high percentage of the build had special drain wire considerations that had to be made to make the communication work ok. New project with a different brand of VFD has come along and we build our first three units and zero of them would communicate over 485 communication connection. (we tested everything before build and it worked) WHY? The cable we were using had 4 sets of twisted pairs inside the shield (so two wires were not connected on either end). Testing on a V350 showed that as long as we had a computer connected to port 1 communication between the PLC and the VFD was fast and excellent TX/RX accuracy, but as soon as we disconnect the computer from port 1 communications would fail to a rate of about 75% packet loss (at slowest communication speeds). We tried different grounding of the shield to no effect, we replaced cables (didn't expect that one to work) to no effect, we took the test VFD from our desk and replaced that VFD with one in the constructed panels (no effect), so then just because there was nothing else to try we took one of the connectors that comes in the box for the V100-17-RS4X Modbus adder card and just twisted that to a standard 3 wire Beldon (really poor connection) and communication success went back up to about 99%. So we soldered 3 of the connectors from the V100-17-RS4X and shrink wrapped it all so that we could ship the 3 panels to their end customers. Then began the process of figuring out the whys and wherefores as to what the heck was going on. Taking new (expensive shielded) cable we stripped multiples back all the way to the metal cased plug and found that the manufacturer had done a good job on construction. We removed just the two wires that were not connected to anything on either end and found that removal of the two unconnected wires help com success rise to the 60% level. Then made sure that no wires were touching out of the remaining 4 unconnected wires and coms rose to a 90% success rate. Then we cut the 4 remaining wires to be about 1 inch long and made sure they did not touch anything and coms rose to about 96%. Then made our own cable with an RJ12 connector to have only 2 (totally unshielded wires with low twists per foot) wires and comes were great. So now we will be buying specialty cables that have only the two required conductors inside them. Thank for reading and I hope our pain can save you some. Keith
  7. Everyone has a bad story about every brand of PLC ever offered for sale if you use enough of them. I have had AB, ABB, GE, EZ automation, Automation direct, Moller, Eaton, Schneider, Siemens all fail at one time or another. There are cases where the Unitronic's PLC has frozen or stopped working. I have had failures for water, H2S, lightening, power surges, line slaps, ambient heat, transformer explosions.... Etc. can kill anything. This is all par for the course if you install enough product. After installing upwards of a thousand PLCs (all brands) I can say that I really like the Unitronics PLC and it is dramatically more durable than other lower cost brands. Sgull is exactly correct on the use of AC snubbers and DC diodes and many problems are fixed by adding these to coils and contact closures. Variable speed drives are very electrically noisy and they affect everything on the same ground circuit and close physical proximity. We have 300-400 PLC units (JAZZ, V350 and V570) installed on VFD applications and the most common thing I have to fight on a regular basis is VFD noise messing with the RS232 or RS485 communications. Just like everything else in life sometimes grounding shields is good and sometimes it is bad, but I have never had a Unitronics PLC fail to work at all. Thanks Keith
  8. I am unaware of any pre-built function blocks that will do the cascading you want. You have to write it out long hand in the nets with timers and compare blocks to make the lead lag control you want. Good Luck Keith
  9. if by cascading you mean lead/lag function then there are several ways to do this but one way is: you tell the system to hold a particular pressure. Run pump 1 only ........ if pump 1 has to run greater than 90% of capacity for more than a programed amount of time then bring pump 2 on line to help pump 1. If the combination of pump 1 and 2 runs for less than say 40% of capacity for a programmed amount of time then turn pump 2 off and let lead pump (pump 1) handle all of the load. Automatically switch which pump is the lead pump when both pumps stop to equalize run time. Or automatically switch after a certian amount of time. If switching on the fly, then make sure that lag pump is brought up to speed before shutting down lead pump to smooth out switchover transition. Thanks Keith
  10. +1 for enhanced Vision controllers also. This is really necessary for OEM applications where the same program is used over and over, but the sensor ranges can always be different from one job to the next. I know that the circular guages are not able to do the integer linking now, but this would be an awsome addition. Thanks Keith
  11. I have looked at your file. You are scaling values into the exact same MI locations that you have designated for the thermocouples on the ATC8 module in your hardware setup. Don't do this. The thermocouples do not need any scalling and the values directly off of MIs 200-207. Delete the scaling blocks and look at it again. The information in the MIs 200-207 should be read with one decimal point implied so for example a number of 506 in MI 200 reads 50.6 degrees C based on how you have your hardware programmed in Visilogic. Thanks Keith
  12. For my part I am looking for an enhanced Vision answer to these requests. Thank You Keith
  13. I have a secondary question. I know that I can only have 64 files without the possible corruption of files. In todays technology can't we manage to either allow more files than 64 per folder or at least allow for more than 4 "Excel" folders. We have customers that 64x4 will only allow a customer to have a very short term of SD card data logging. In this case the customer is testing aircraft radiator sections and each and every part must have its own file name so that it can be stored with all of the other required files and paperwork relative to the specific part number tested for tracking. Thanks Keith
  14. I have uploaded a demonstration program on at least one way to show two tank levels in a single tank space they way you want. The program is competely simulated but you will be able to get the idea of what needs to be done. Thanks Keith oil and water tank level simulation.vlp
  15. Version Visilogic V570 Version 9

    473 downloads

    This program shows a way to indicate two liquis levels in a single tank. Since you can not overlay two bar graphs on top of each other this is a work arround to be able two show two seperated fluids in the same space. Oil and Water in this case.
  16. I am reading what you have said and one piece does not make sense to me. You say you have short wires connected. What does that mean? If you are saying that you have a single wire shorting (for example) T0+ to T0- then this will never work. You can make a home made thermocouple out of any thermocouple wire set by stripping and twising the positive and negative ends together on one end and then correctly connecting the other end to the "T" terminals. (The wires can not touch anywhere exect the end you twist together or it will not work correctly) The wire with the red insulation on it goes to "T-" and the other color (color depends on thermocouple wire type, K type is yellow) goes to "T+". The wire in your case must be K type thermocouple wire and any other wire types will not work. Good Luck Keith PS: In your first post you said that all inputs are maxed out and one is different. Are these numbers the same all of the time........Paying attention to the one that reads 11460 even if nothing is connected to the input in question on the IO-ATC8. If the numbers do not change then you are not communicating between your PLC and the EX-A2X module. When communications is lost the numbers in the MI get fixed in place wherever they were last. Test this by forcing a value into one of the MIs you used to map the thermocouple inputs .................. If you can change the value of the MI you are not communicating .............. If you can not change the value from what is there already then you are communicating.
  17. Hi Johnny, The EX-A2X is dramatically lower cost that the EX-RC1 and you need at least the EX-A2X module to be able to use the IO-LC1 module. Have Fun Keith
  18. Just my perspective, SInce you have the need for so many transistor outputs and the load cell requirement I would use the following: V350-J-T38 EX-A2X IO-LC1 And since you have VFD to communicate with I would strongly suggest that you still add a V100-17-RS4X You will want to set termination for both the VFD and the PLC as this really seems to help out with VFD noise. Your com cable needs to be shielded and the drain wire needs to be as short as possible to a good ground source. The com port on the V350 is not isolated and an isolated port will help. We ship thousands of VFDs every year and have great experience with the trials and tribulations of comm errors in the presence of VFDs. I know that this is not as low cost as the SAMBA but you will be much happier not having to dodge the limitations of the samba given all of the thing you are trying to do. On the stepper, I never use them so I am unable to give you and answer to that question, but I am sure someone else will. Good Luck Keith
  19. On Question 1 yes VFDs can cause the USB connection to stop between a laptop and the PLC. What happens is the VFD is imparting noise into the localised earth ground and it gets picked up by the cable. A ferite core as you have seen can sometimes (not always) correct the issue. At his point I do field reprogramming with an SD card unless I am needing to look at operations in a Visilogic program live to make changes. I have found that older serial connections (if your laptop has a serial port) and the cable that came in the boxes before USB cables can work better in noise environments. On your second question. I have never had noise interupt calculation in the PLC. (I have had noise stop a PLC all together but not creat a hiccup in operation. Using positive or negative transitions can have wierd effects. Usually if you look into it far enough you find that there is something that created a delay in the program and the transition (for lack of a better way to describe it) gets missed. Another way to get to the same place is to use positive transition to increment an integer to then use the integer not equal to 0 to make the math run and at the end of the math line store a 0 back into the integer. Finding little gremlins like this can be difficult, so sometimes working around the issue becomes easier. If you find that noise is the issue it would be nice to hear back from you on this. With VFDs the ability to have an excellent ground makes all the difference int he world. The better the ground (ground wire needs to be same gauge size as the 3 phase wires) the faster the stray voltage the VFD imparts into the transmission cables can be drained away. You will be able to see the voltage with a scope. Good Luck Keith
  20. I am with Joe on the desire to have real 120VAC capability brought more into the main stream of Unitronics products. Unitronics is the only PLC manufacturer we work with that has no real 120VAC capability. No AC input snap I/O modules, no 16 or 32 channel AC input add on modules and no triac output capabilities at all. There are industry segments I would like to use Unitronics on but am destined never do so because of the cost to get AC I/O and the amount of space required to package the I/O. How about a nice V200-18-E6B module repurposed to have AC inputs and leave everything else the same if possible, the addition of a 16 input module, and 16 triac output module . There are literally millions of burner, boiler, furnace, flare, thermal oxidizer, impingement, ..............ETC application installations that do not use DC voltage for any of their shutdowns .........everything is 120VAC. The industries that use any of the US providers of flame safety equipment are always going to be 120VAC and will never ever change to 24 VDC. Even if you are making a custom DCS system from scratch there isa need to have AC I/O. The financial benefits to expanding Unitronics' capabilities to include 120VAC would be huge. My humble opinion Keith
  21. This is one of those multiple possible solution questions, but because of the size of data you want to send you are pretty well limited using the modem to Unitronics solution. I am not sure that you will like the answer very much, but to send a large quantity of data what we have done in the past is to make an ethernet connection with an "Embeded arm" controller sending an email with the file you want to transmit to the embeded arm product (you have to program that to be an email server) and then used it to make the connection with the modem since it will allow a full speed connection to the modem up to the maximum the enfora will allow. You can use a celular router directly (again using an ethernet connection) but the Unitronics will perform poorly unless you have a 3G or 4G connection. See Older Post from Jweav2223 that does this router method. On the plus side the method used in that post has the benefit of being low cost. Thanks Keith http://forum.unitronics.com/index.php?/topic/2692-ethernetcellular-commnication-ios-app/
  22. Knowing that you have a 4-20ma temp sensor that you have to scale to show -60 to 60 on a screen. After you linearize the temperature everything can be compared to the final degrees celcius engineering units you are using so your min and max limits should be -600 to 600 (I am assuming you will have 1 decimal place. Good Luck Keith
  23. A couple of things that might help (or maybe not). When connecting Vision or Enhanced vision controllers to a modem you can never have anything different than 9600. The modem is able to be faster and the PLC is able to be faster, but the behind the scenes programming in Visilogic willnever give a successful connection at anything other than 9600. On your modems connections to cellular service. The Enfora modems are only capable of 2G service. Depending on where you are 2 G service may not be available. 2G service will be gone nationwide in the USA in 2017 from all carriers and At&T has been dropping 2G service early in several location in the USA. Check your SIM card carrier and thier coverage maps to be sure that 2G service even exists where you are trying to use the modem. Thanks Keith
  24. I am glad you have a solution but you should have been able to save yourself this step. The fireye boiler controller should have an address that is the scaled value of the pressure already calculated. I am curious (if you dont mind) what model of Fireye controler are you using? Keith
  25. Since the PLC will not execute the write commands quickly enough over time we have installed a time function that after the write time exceeds 1.5 seconds we are just going to create a new delimited file. (1.5 seconds is the maximum time allowed and still be able to write the next line of data when it needs to be written). This is a very ugly solution and should not really be necessary, but oh well. No Im sorry it is completely unacceptable to write the data into multiple lines. The project involves graphing each completed action and holding historical data for each action the pain involved on the excell side is just too high. Thank You Keith
×
×
  • Create New...