PID_Temp Siemens TIA Portal

[LB90]

Hi all,

This is my first post, so please be gentle if possible.

I'm building a project using Siemens TIA Portal V13 SP1 Update7.

It's a fairly simple application, and I'm using 'step logic' to make it as clear as possible.

I need to use a PI controller to control a room to a set temperature. For this, I'm using PID_Temp.

I only want to enable my PI loop when in a certain 'step' of my program. So I've put this condition on the 'EN' of my controller.

Forgive me if this is a stupid question, but do I still need to change my controller Mode to 'inactive' once I come out of this step? As the enable conditions for the controller to function will no longer be met.

As you can probably tell, this is my first time using a PID controller.

Any help or guidance would be appreciated.

Cheers,
LB

 

[boneless]

I would let the mode be automatic and just set the manual enable bit when you don't need it.

Personally I do not like to use the EN with the PID blocks

 

[wimpiesplc]

I would let the mode be automatic and just set the manual enable bit when you don't need it.

Personally I do not like to use the EN with the PID blocks

PID or not, when disabling the EN you actually pause all the logic in the block. up to you if you want that or not

 

[chrispdf]

I second boneless regarding PID blocks

 

[LB90]

Thanks for the input everyone. Think I'll move away from having conditions on the EN of my PID block.

Can anybody shed some light on the difference between manual mode and inactive?

My uneducated guess would be that manual mode sets the output of the controller to a set value, regardless of setpoint value or measured variable, and inactive effectively disables the loop? Any pointers would be useful.

 

[DeKemp]

My uneducated guess would be that manual mode sets the output of the controller to a set value, regardless of setpoint value or measured variable, and inactive effectively disables the loop? Any pointers would be useful.

Asuming the 1200/1500 block is more or less the same as the 300/400 block

basically there are the following possibilities.
OFF :Controler is doing nothing
Auto SP :Controler is fully auto trying to regulate to the setpoint
Manual SP :Manual value of the setpoint
Manual CV :Manual value of the actuator

 

[LB90]

After reading the surprisingly helpful help file with TIA, I notice that when mode = 0 (inactive) the controller output (PIDOutputSum) is set to 0.0. This is actually what I want for my application.

After delving a little deeper into the surprisingly helpful help file, I came across this comment regarding mode parameters:

"With a rising edge at ModeActivate, PID_Temp switches to the operating mode saved in the Mode in-out parameter."

Does this mean I could change the mode to inactive by simply using a MOVE operation to move 0 to mode, and then set the ModeActivate bit?

I won't get my hopes up.

Thanks

 

[Pete.S.]

Manual SP :Manual value of the setpoint
Manual CV :Manual value of the actuator

Sorry for the hijack, but what does these modes do?

I've only ever seen one type of manual mode and that is to set the output value manually (0 to 100%).

 

[DeKemp]

Sorry for the hijack, but what does these modes do?

I've only ever seen one type of manual mode and that is to set the output value manually (0 to 100%).

In normal operation the program sets the controller to Auto mode with a auto setpoint. However sometimes you want to manual change this value.

In short,when activating ManualSP it overwrites the auto setpoint that goes into the PID block with the desired manual setpoint.

Very handy and requires not a whole lot of work.

 

[Pete.S.]

In normal operation the program sets the controller to Auto mode with a auto setpoint. However sometimes you want to manual change this value.

In short,when activating AutoSP it overwrites the auto setpoint with the desired manual setpoint.

Very handy and requires not a whole lot of work.

Thanks.