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About Addohm

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  1. The first question is very simple.  They are relays.  In other words, they are switched contacts, or switches.  That means the PLC closes a pair of contacts to create continuity between two contacts.  The most important thing is to make sure you don't exceed the rated voltage or current of those contacts.    You our should also keep in mind that relay contacts are physical and have a far shorter life span than transistor outputs.  I say that because if you're cycling the solenoid very often (I mean x times per minute), the life of the relay will be short.   The second question is a bit confusing.  Are you saying that you're using a push button switch to energize a relay?  If so, you go by the relays COIL voltage; it depends on what you buy or what the customer has already.  If your push button is going into a PLC input, you obviously need 120v.  I guess my question is, what are you "turning on" with your push button?  
  2. VBA code problem...need ur help to find the bug

    Where are you declaring txtHorno?
  3. Wiring Diagram

    Need more information. What is the problem in your mind? There should only be DC voltage at that connection. With the negative lead of your meter on that point, and the positive lead at any point of the positive DC supply, you should see voltage.
  4. MicroLogix 1400 Lockout/Disable.

    Can you set the major fault bit in a rung? I've never tried it. That will put the processor into a hault state and all outputs would shut off. It is S:1/13 if I remember correctly. Another method is to just set it to program mode and create your own LCD display, and set the processor to start your LCD display instead of the default.
  5. String Input and PV+700

    I figured out a way. We only have 8 product numbers, but have 9 string words in the file. In the program I define an "new product number" by subtracting 80 from the current product number. I wrote to the 9th string from the HMI, and copied the 9th string to the string file:[new product number] when enter is pressed.
  6. String Input and PV+700

    I need to use a stringinput button to allow a user to modify the recipe name of a product. The recipe names are stored in ST99:0 through ST99:7. The product number itself is a value of 80-87 and that value is stored in N181:6. These are not original options so I am trying to find the best way to integrate. Anyway, what my original thought was to have a rung that subtracts 80 from the product number to give me a value of 0-7 and stores it in N181:5, and then write the string to ST99:[N181:5]. I'd never tried doing that in a PV before, and found out quickly that you can't do that. I expected that was the case. Has anyone got another suggestion for doing this? Adding another string file (or any file for that matter) is not an option (req. a download and conversely stopping the machine. Thanks, Adam