Hi All,
I am currently at the beginning of a new project for writing a PLC program (using CCW) for an old sugar centrifugal.
Most of our factory is Honeywell CEE function chart so I am wanting to make something resembling what would normally done in the CEE (Which would be individual Control modules for the devices that are controlled by a Sequential Control Module).
Building the UDF (device control block that handles the command, input status and permissive and override interlocks) is relatively straight forward, the only thing I am struggling with is the Input command to the UFD itself.
Typically what would happen in CEE for example if State0 was requested on the InputCommand to the block and an override interlock for another state was ON or the state0 permissive was OFF the block would reject the change to the InputCommand.
Another scenario would be that if the block was in State0 and the override interlock for State1 turned ON the InputCommand would then need to be set to State1 as well.
The problem is, is that the ST in the UFD cannot change the value of a variable that is on the input side... so I am at a loss for what to do about this.
Any thoughts?
Thanks.
Note: I do have a ladder program for one of these centrifugals (would require a bit of modification) but ladder is very problematic for the electricians and myself to easily identify operational problems.
I am currently at the beginning of a new project for writing a PLC program (using CCW) for an old sugar centrifugal.
Most of our factory is Honeywell CEE function chart so I am wanting to make something resembling what would normally done in the CEE (Which would be individual Control modules for the devices that are controlled by a Sequential Control Module).
Building the UDF (device control block that handles the command, input status and permissive and override interlocks) is relatively straight forward, the only thing I am struggling with is the Input command to the UFD itself.
Typically what would happen in CEE for example if State0 was requested on the InputCommand to the block and an override interlock for another state was ON or the state0 permissive was OFF the block would reject the change to the InputCommand.
Another scenario would be that if the block was in State0 and the override interlock for State1 turned ON the InputCommand would then need to be set to State1 as well.
The problem is, is that the ST in the UFD cannot change the value of a variable that is on the input side... so I am at a loss for what to do about this.
Any thoughts?
Thanks.
Note: I do have a ladder program for one of these centrifugals (would require a bit of modification) but ladder is very problematic for the electricians and myself to easily identify operational problems.