Mendon Systems

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Posts posted by Mendon Systems


  1. The basics are:

    1) Use the FIND$(660) command to return the position of the first comma in the string in hex

    2) Use the LEFT$(652) command to extract the characters to the left of the comma to another string

    You will probably want to subtract 1 from the hex value returned by the FIND$ command so that you don't get the trailing comma when you use the LEFT$ command. You may also want to use the DEL$ command to clean up the data left in the receive buffer.

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  2. You need to display the "Address Reference Tool" window on the CX-P screen. Each time you select an object in the program by clicking on it that window will display every program rung which references it. When you click on a reference in that window it will take you to the corresponding rung in the program.


  3. OK ... I see what you are after.

    Whether that will work or not depends on how much inrush current those VFD's draw. I would not be at all surprised if you wiped out some fuses. Is there a way that you could power up the VFD's one at a time?


  4. The default IP address for the ETN is 192.168.250.node# (node number set on rotary switch). There is a small chance it might still be set to that IP address. If it is you must use a PC set to the same subnet to establish communication with CX programmer.


  5. You still haven't told us which PLC you have, but assuming that it is reasonably current you should be able to use the ++(590) and --(592) instructions to manipulate the value in a DM or H register. Those register values will be maintained during a power cycle.


  6. One thing to keep in mind when using immediate refresh:

    The I/O point referenced by the immediate refresh can change state in the middle of a program scan which could mean that any rungs which reference the I/O point before the refresh get different results than those after the refresh. In most cases this won't make any difference, but there is a possibility that it could cause weird results in the logic which are extremely difficult to debug.