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Joe Tauser

MVP 2023
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Everything posted by Joe Tauser

  1. Your sequence does not need the speed described by Simon's post. Take a look at the state machine example I posted here: http://forum.unitronics.com/index.php?/topic/1993-concrete-batching-project/ If you understand this programming concept, it would be easy to add a state that counts to N as part of the sequence and then finishes when your counts are done. Joe T.
  2. Can you describe your sequence? What is the model number of the PLC you are using? Joe T.
  3. Jeff, You are correct in picking the negative transition instruction to determine when the input goes to a logical zero. The output of the instruction will be on for one scan, which you can use to make another action. On a larger scale, if you are new to PLC's I would highly recommend building a simulator with 24V lights and switches and wire it up to your PLC. I've used a cardboard box as the enclosure for this - you don't have to get fancy. Play with your program on the simulator before you hook the PLC to the actual press - this is not the type of machine to make programming mistakes on. Also make sure you have an adequate safety system on this thing, and it should be totally outside the PLC. You can have an input the PLC reporting that the safety system is satisfied, and make sure any PLC outputs controlling moving parts that could hurt somebody run through a safety relay tied into the system. Depending on how old the punch press is, you may have to add considerable guarding, light curtains, door switches, etc. I have done a couple of press retrofits and the program is usually not complicated, but you need a healthy dose of CYA when you get involved with one of these. Joe T.
  4. Jerin, Google is your friend- http://www.mesta-automation.com/modbus-with-c-sharp-libraries-examples/ Joe T.
  5. There have been requests for a Unitronics mobile app but as of now it doesn't exist. The trend UTR file format is proprietary. There are some things the Creators won't give up, this being one of them. You could store the trended data to a csv file on the SD card using the SD Excel utilities and extract it from there. You could also write the data to a data table and read it that way. Look at the PCOM Protocol description to see if there's something you can utilize. Joe T.
  6. I had a customer ask about network printing from the PLC and did some digging. The PCL5 language dates back to the LaserJet III and further information can be found here: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=bpl04568&jumpid=reg_r1002_usen_c-001_title_r0001 This page includes links to the actual PCL Technical Reference Manual needed for creating PCL commands. I will be trying some of this out and I'll keep everyone updated. Joe T.
  7. You're running into a physical system repeat-ability problem. The time between when the sensor responds and PLC scans the input and the motor actually stopping will have a variance to it. What kind of accuracy are you trying to hold? How fast does the motor move the part? What is the resolution of the encoder? You'll probably need to write some code to slow down the motor when you get close to the setpoint and "creep" the part to it's final position. Joe T.
  8. You're right, Cara. This feature deserves more- [media=]http://www.jtauser.com/Unitronics/Hallelujah.mp3[/media] Joe T.
  9. This is more of a programming style question. Your batch can be broken down into a definite sequence, and I find the easiest way to program a sequence is to make it into a "state machine". You start by drawing your sequence as a flowchart on paper and assigning step numbers to each operation. Then use a pointer in the PLC with equal blocks to only allow one step (state) to be active at a time. You will define a state that adds each ingredient and jump from one state to the next to add additional ingredients. I have attached an example. Joe T. state machine batching example.vlp
  10. Simon, you beat me to it. If I may expand, I would like to sing praise from mountains on high that we finally can back up our data as part of the program! Cara - it doesn't need to be in Excel. It just needs to be, and now it is. Why didn't you tell us this was coming? Joe T.
  11. Simple, cheap, and old-school. The only problem is if one of the 100 ohm pots gets disconnected you'll get 500V on the input of the PLC, which I don't think it will like. Putting components like resistors in control systems always makes me nervous. If I was doing it I would spend extra money and err on the side of caution- http://www.nktechnologies.com/voltage-transducers/vtd-dc-voltage-transducers.html At $180 they're not the cheapest things in the world but they won't come back to bite you. Literally. Joe T.
  12. You need to power the module as well - see page 5 of the data sheet. For the outputs you need to run power to V1 and 0V. Joe T.
  13. I would seriously consider using ML's for your math. Are you familiar with the concept of a virtual decimal point? Joe T.
  14. Good job on a post with all the needed information! You've got your X's and Y's backward. X is the input (raw analog) value, and Y is the output (scaled) value. I checked your program and the linear block is programmed right. What kind of 4/20 source are you using? Is it a 2-wire transmitter simulator? If so, you connected it correctly. If your 4/20 source is a true current source then connect + to the analog input and - to 0V. When you're having trouble with an analog input the first thing to do is check your sanity with a multimeter. Disconnect the input from AI 2 and measure the resistance from the input to 0V- if the jumpers are set right for current you should get 37 ohms. If this checks out, put your meter in current mode and insert the meter in series with the analog input to measure the actual current. If you don't have a valid electrical signal then the PLC will report nothing. If it checks out electrically, go online and see if you get a raw value in MI 0. Joe T.
  15. Glad to hear you got it working. I've often found high baud rates to be problematic on RS485 when communicating between devices. I usually use 19.2 or 9600. joe T.
  16. 1. Take the terminators off one at a time and see if it helps. Each terminator lowers the RS485 signal level by some amount and your converter may or may not be translating the data properly. 2. Google "free modbus master" and see if you can find a program to run on your PC to query your slave devices with the RS232->485 converter. You need to verify that your 485 network is wired correctly. I've often gotten A & B backwards (no they are not the same between all manufacturers). You also need to verify your baud rate and parity settings. I've found this much easier to do on a PC. Joe T.
  17. Sweet! You'll find no shortage of people on this forum trumpeting the advantages of Unitronics. I've programmed many of the PLC brands out there and firmly believe that Unitronics is the best bang for the buck, hands-down. There's nothing I can't do with it. Look into what you can do with the Ethernet port and the SD card. You will be amazed. Joe T.
  18. I use Remote Access and the "Save to Excel" function to store the value of the operands. Then reverse the process to load specific blocks of operands into memory locations in the PLC. I really, really, really wish this functionality would be added to Visilogic. I've asked for it a bunch of times. Joe T.
  19. You're going to have a problem with this one. 1800 RPM translates to 30 rev/sec - at 2048 pulses/rev the resulting frequency is 61440 Hz - the maximum input frequency is 20 kHz. If you were to put the encoder on the output shaft of the gearbox your maximum frequency will be 614 Hz, which will work fine. Can you do this? Can you slow the motor down as you approach the setpoint for precise positioning? No, an M91 is not the same program, but it is similar enough to use for testing the encoder. The maximum input frequency input on an M91 is 10 kHz. Joe T.
  20. I believe adding a pair of these to the sides of the enclosure will fulfill the "handheld" description: Joe T.
  21. That is a neat doo-dad, but with a 5.6" display I don't know how "hand-held" it is. Still it's a good suggestion. It would be easy enough to mount a V570 or a V350-35-B1 in a small plastic enclosure and run the expansion cable and power wires in woven sheathing to make an umbilical cord. Joe T.
  22. You'll need to run the Z pulse to an input and put an interrupt routine in with an Immediate Input function to catch it. You can then reset the counter register. How many pulses does the encoder have and how fast is the shaft rotating? Joe T.
  23. I'm with Emil. Don't use a V120 on a new installation - use a V130 and get the Ethernet card for it. You can always put an additional Ethernet switch anywhere you want to and get additional Ethernet ports in the panel. Ethernet is so much easier to implement over RS485 or CANbus unless you have a distance or speed issue. If you need to throw data between the controllers you can use the Modbus IP blocks. Joe T.
  24. I have connected a stepper driver in exactly the way you describe and it works fine. Let's look at the design specifics- Your control specifies a 5V input pulse, which is extremely common. It has an internal resistor in series with the opto-coupler to limit the current to about 10 mA at 5V. As Simon mentioned, the on-state voltage drop of an NPN output is 0.4V, so we can effectively ignore it. The voltage the resistor will need to drop is 19V at 10 mA, resulting in a series resistor size of 1900 ohms, or the 2K you mention. The power rating of the resistor is 0.2W, so you really only need a 1/2W resistor. If you can locate a 2K resistor, great. A 2.2K is much easier to come by and will result in slightly lower current through the opto-isolator but it will still work. This is the value I use. Joe T.
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