Emerson Exchange 365

PID Loop Increase to close function

Hello Experts,

I was testing the functionality of the PID FB's increase to close option, but even after enabling it, no effect on output was observed.

And when I tried it with an AO block connected to the output of a PID FB and the following configuration, I noticed an effect on the overall output.

PID1/IO_OPTS = Increase to Close Disabled

AO11/IO_OPTS = Increase to Close Enabled

Can anyone tell me if I can achieve the same result without using the AO block and why there was no change in the output when using only the PID block?

• AO
• control studio
• PID
• FBD
• DeltaV

Nirit

• 14 Dec 2021 6:52 AM
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1 Reply

• Mark Bendele

  

  • 14 Dec 2021 1:43 PM

  The following is from books online for the PID function block. "Increase to Close — This option has an impact when a device signal tag is configured in IO_OUT. Increase to Close causes the milliamp signal on the analog output channel to be inverted in Man mode (and in Auto mode). That is, a full scale value on OUT will result in 4 mA on the channel. When IO_OUT is configured, the OUT value is the implied valve position and is not inverted when Increase to Close is True." Note it says the OUT value is not inverted. But the same is not true for the AO block, for which books online says "The converted percent value is inverted and stored in the OUT parameter, except in Man mode. In Man mode, the OUT parameter is set manually.

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