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Author Topic: DL06 -CMPV  (Read 6480 times)

malcolm58

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DL06 -CMPV
« on: October 19, 2010, 02:35:55 PM »
Hi,
I am having trouble with CMPV.
In the first stage I load an “A” in two separate V memory locations using a VPRINT command.
In the second stage I compare the two v memory locations, and when they are equal or unequal I can not get the SP61 to change.
Do you have any ideas as to what I am doing wrong?
Ultimately I want to read [AIN] from a computer and compare the characters.
Malcolm58

b_carlton

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  • Posts: 606
    • thePLCguy
Re: DL06 -CMPV
« Reply #1 on: October 19, 2010, 02:55:25 PM »
Are you looking at the state of SP61 directly? Are you passing it to a 'C' bit? If you are using an OUT command in a stage then it may be turning off as the stage is exited. Try this:

In the first stage load the two 'A' registers and also do a reset (RST) of the 'C' bit used.

In the second stage have the true state of SP61 SET that C bit. The view the C bit.
An output is a PLC's way of getting its inputs to change.