PID Control on LS XEC PLC Losing Parameter changes

DS4275

Member
Join Date
Jul 2006
Location
Durban
Posts
3
I am using a LS PLC - DR60SU - to control various control loops. I have set up the PID loops in the PLC and am using an HMI to set the sepoints and PID parameters.

The problem that I am having is that the PID parameters are not retained when the power to PLC is cycled or the PLC is changed from run to stop and back to run mode. The parameters always revert back to the parameters set in the original - Internal parameters/ PID settings. Any changes made on the HMI or through the Autotune function are lost.

I have done a work around - copying the parameters into a retained memory area and the writing them back on the first scan. I am not happy with this, the PLC should retain these values without having to add all the extra code. In the manual it is indicated that the K area of memory is automatically retained, the problem I think is that the parameters are overwritten when the PID loop is initialized.

Is there any way to prevent the parameters being overwritten ?

Regards and many thanks


Edward
 

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