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mcmahoney

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Everything posted by mcmahoney

  1. I have an application that has to communicate to the SCADA system with Allen Bradley Data Highway Plus. Is there a way to do this with the communication protocol? I need to know if I need an external converter or can i work directly from the port? Thanks.
  2. I have a project that reads the 16 bit registers from a slave device and have a problem with reading the unsigned value. I have worked out a way to read the value. if the value is positive, then I read it directly. If the value is negative, I add the value to 65535 and store it in a long location. I was wondering if there was a cleaner way of doing this.
  3. Is there a way to delete the files from an SD card? I am writing files to the DT folders and would like to delete these files using the ladder logic.
  4. I was downloading the updated OS to the PLC and while the program was in step to of downloading binaries, it suddenly popped up a message that it loas communications to the PLC. Now the PLC doesn't run and I can't communicate to it at all. Anyone know if there is a way around this problem or is it gone because the flash was erased? Any help would be highly appreciated.
  5. I am using a string library to list strings in a text box. I am using the indirect method. So I have slected a MI for the row number in the string library to be displayed. It seems to work fine, except when I change the string row number, the string that was in the text box originally doesn't go away, it just gets written over with the new string. I have added, for test purposes a screen refresh button and the origrinal text screen clears and the new string is only visible. Do I have to do a screen refresh anytime that I change the row number in the string library?
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