Sorry for this newbe question, but I am working on cleaning up my act using producer/consumer kinds of event driven state machines. To do this effectively, it is handy to create a type definition for the enumeration control that defines the potential states of the consumer loop. I don't understand any of the discussion in the books I am reading. I have simply placed an enumeration control on the front panel and edited the state names, using them to define the Queue for the consumer loop. However, when I use other queue functions, and create a constant for the state to put on the queue, that constant gets pulled at the time it is created. If the list of states is changed, the queue element using the previously defined constant shows a coersion symbol (little red dot), and the constant does not contain the new potential state ... is that what the type definition does is propagate that definition to the constants so they keep up with additions to the enumeration list...? I have been messing with a short example to see how all this works. If someone could help me with the type definition thing I would appretiate it. Thanks Hummer1

Hi Hummer1, Do the following: 1. Under the "file" menu, select "New..."2. A dialog box will pop up. Select "custom control" and click "ok"3. A new front panel will pop up, called "control1.ctl". Put your enumerated constant on this new front panel. Add all of your states for your state machine, the way you have been doing.4. Under the menu on your new custom control, you will see a field labeled "control". Click on it and choose "type definition" (or "strict type definition").5. Save your new custom control as "states.ctl" or "enum.ctl" or whatever name strikes your fancy. Now go back to your main VI. From the "controls" palette, click "select a control". Choose the typedef you just created. Put it on the front panel. Right click on it and select "find terminal". Your block diagram will pop up and the control's terminal will be highlighed. Right click on it and select "change to constant." You can now wire this constant into your queue. Do the same thing for any other subVIs that use the same queue, so that they're all referencing the typedef. When you want to make changes to your control, open it the same way you'd open a VI and make the changes. Then, under the "file" menu, select "Apply changes". The changes you made will propagate through to all of your VIs. I've attached a little example of a typedef for you.Diane

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how do you create a type definition for an enumeration

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My final example using each of the type definitions you were kind enough to show me how to do.

I opened a new control, put an ENUM on it, set the control/typedef/stricttypedef option to typedef...saved it then moved it onto the block diagram, changed it to a constant and used it to define the queue, and all other instances where a queue might need to access a state in the ENUM type definition. I can edit the type definition of the ENUM to add and delete states.

I opened a cluster on the front panel, moved two sliders into it, then went to the edit control and selected the customize control option. Set the control/typedef/stricttypedef option to typedef. Used the definition on the block diagram to be the input to the bundle by name which created the type defined structure for all the variables associated with the sliders.

So, run the vi... It comes up, initializes the states of the sliders, goes to the update state and updates the indicators, then goes to the idle state. pressing other buttons causes the other states to be entered, but all of them but state 3 proceed to the "idle state".

This has been incredibly helpful.

Next...I need to work on error trapping and handling using an error handling case structure with queue...Hope you guys are up for that.

Thanks again...

Hummin' along again.