PRD Mode on Yokogawa Centum VP


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Cascade controllers in Yokogawa Centum VP and Centum CS3000 allow the controller to be put in PRD mode. This mode bypasses the secondary (slave) controller and connects the percentage SV input to MV directly. That's why it is called "Primary Direct".

Normally, it is not easy for the operator to put the controller in PRD mode. The standard mode selection window displays three options, MAN, AUT and CAS. However, the operator can put the controller to PRD mode from controller's tuning Window. We don't use the PRD mode and fear that if the operator presses the PRD button in tuning window by mistake, it may lead to undesirable operation due to sudden change in MV.

Is there any way to remove or disable the PRD button in tuning window? I have some idea that the toolbar can be customized from registry, but I couldn't find relevant registry settings.