Guy and Seth on SimulinkAugust 13th, 2008Dynamic Mask DialogsWhen configuring a Simulink block, you usually use a graphical user interface (GUI). In this post I’m going to investigate the basics of programming a dynamic GUI using the mask editor. The Saturation block features In my last post, I introduced the example of a Saturation block that can use fixed limits set in the mask dialog or dynamic limits set via input signals. Here is an animation of the mask GUI that configures the block for these different modes.
When the Upper and Lower Limit Sources are internal, the block has a single input port. When the Upper/Lower Limit Source is set to external, the block grows additional ports to accept signals that provide those limits. Mask dialogs can associate actions with its components. Most Simulink block GUIs have a standard row of buttons along the bottom. These four buttons provide a consistent interface for Simulink blocks, and when you use the mask editor, you get them free.
I added the other elements of the Saturation GUI through the parameters tab of the mask editor:
Each parameter of the mask has a row in the Dialog Parameters table. The Prompt (1) is the text displayed next to the widget that sets the value. The Variable (2) is the name of the variable set in the mask workspace when the GUI is applied. The Type (3) controls the widget used for the parameter. You can choose edit, checkbox or popup. I picked popup for the parameters Upper Limit Source and Lower Limit Source parameters. I set the popups (4) to display internal or external. The Upper Limit and Lower Limit parameters use the edit type. Each of the parameters also has an Evaluate (5) and Tunable (6) setting. I want uplim and lowlim to have the values that are entered into the dialog. If a MATLAB expression (like 'sin(x)+1') is used to set the value of the Upper Limit, I want that to be evaluated. I don’t want the variable to hold the string that was typed into the edit field. Tunable means the value of the parameter can change during the simulation. Upper and Lower Limits will be tunable through the dialog if internal limits are used. The Limit Source parameters are not tunable because they change the configuration of the block. It is not possible to reconfigure the model structurally in mid simulation. Dialog Callbacks Dialog callbacks (7) are called when the parameter is changed in the mask. Use dialog callback for error checking and controlling the visibility and enabled/disabled setting of other parameters in the mask dialog. In the Saturation mask dialog, the Upper Limit Source and Lower Limit Source parameters fire a Dialog callback when you click on them. This is the mechanism for enabling and disabling the Upper Limit and Lower Limit Edit fields in the GUI. Key Point: Just like a handle graphics GUI, the Dialog callbacks run in the MATLAB base workspace. Program the callback as if you are running it from the MATLAB command line. Here is the uplimsrc_cb called when the uplimsrc parameter changes: % uplimsrc_cb Dialog Callback function uplimsrc_cb(blk) en = get_param(blk,'MaskEnables'); switch get_param(blk,'uplimsrc') case 'external' en{2} = 'off'; case 'internal' en{2} = 'on'; otherwise disp('Should never get here') end set_param(blk,'MaskEnables',en) When you click on the uplimsrc popup and change it, this callback fires. The callback:
If the block uses an external limit source, the corresponding fixed limit is disabled.
Mask Dialog Callback Confusion I have found callbacks that modify the block contents are a major source of problems. Key Point: The mask dialog callback is for modifying the mask dialog, not the system. The documentation on mask callbacks also discusses this subject. If you need to modify the contents of your system, do that in the Mask Initialization, which runs when you click the Apply or OK button. That will be the topic of my next post. Now it’s your turn Do you have dynamic masks? Leave a comment here. 17 Responses to “Dynamic Mask Dialogs”Leave a Reply |
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In video stabilization demo provided with video and image processing blockset, the ‘Stabilization’ block has a mask that takes parameters as:
pos.template_orig = template_orig;
pos.template_size = template_size;
pos.search_border = search_border;
Initial inputs are acquied via user dialog. My question is how can i make it dynamic? i.e. pass these parameters to the block in runtime rather than specifying them before running the simulation.
Thanks
I wanted to add another tip. When referring to the mask parameters within your callback it’s very useful to create a C-style enumeration instead of calling them explicitly by numbers. In the above example, change the callback M file to:
% uplimsrc_cb Dialog Callback
function uplimsrc_cb(blk)
UPPER_LIM_SRC = 1;
UPPER_LIM = UPPER_LIM_SRC + 1;
LOWER_LIM_SRC = UPPER_LIM + 1;
LOWER_LIM = LOWER_LIM_SRC + 1;
en = get_param(blk,’MaskEnables’);
switch get_param(blk,’uplimsrc’)
case ‘external’
en{UPPER_LIM} = ‘off’;
case ‘internal’
en{UPPER_LIM} = ‘on’;
otherwise
disp(‘Should never get here’)
end
set_param(blk,’MaskEnables’,en);
This comes in very handy for masks with a large number of parameters and also if you need to add / remove a parameter from the mask.
Ashish.
What if I want to have a parameter that is only visible if another parameter gets a certain value ? For example a popup that is hidden and only visible when I select a checkbox. What if the values of a popup are subject to another popup ? Think of countries and states.
Mahmood,
>> pos.template_orig = template_orig;
>> pos.template_size = template_size;
>> pos.search_border = search_border;
Both template_size and search_border affect the size of Simulink connections (wires). Simulink requires fixed size connections during runtime, therefore this information must be gathered prior to running the model.
template_orig provides location information. It does not affect wire size, therefore it can be set dynamically during runtime. Although the Stabilization demo doesn’t show you how to do it, it’s possible to turn the mask input into a port to the Stabilize subsystem.
Witek
@Mahmood – thanks for the good question. I’m glad Witek was able to respond. (Thanks Witek!)
@Ashish – This is an excellent tip and a very clear example. I’m sure I will be using that in the future.
@Hans-Werner – The hidden/visible state of a mask widget is controlled by the MaskVisibilities parameter. It uses a cell array of ‘on’/'off’ values to control your mask. Try:
get_param(blk,’MaskVisibilities’)
The method I have used to set values of one popup based on another also involves MaskVisibilities. This only works if you have a small number of groups to switch between. Create a separate popup for each group and make the appropriate popup that corresponds to that group visible, and all the alternatives invisible. The programming gets very complicated to do it this way. The other option is to build your GUI using GUIDE and replace the OpenFcn for the block.
Thanks for the respsonse. My other question is, Tracking with zoom-in/out requires to change the template size from frame to frame, in this particular case, how the template size can be varied dynamically during simulation? If not, what alternate method can I try from within Simulink?
Thanks and Regards
Mahmood
Is it possible to dynamically change the MaskStyle, i.e. change the text entries of a popup parameter?
For example, I would like to have a popup, whichs offers the choice between different parameter files I can load for the block. Now, I don’t want to alter the popup manually everytime I add a parameter-file to the list in the library block but rather scan a folder containing the files and create the popup list accordingly. Whenever I try something like this in the dialog callback with
set_param(blk,’MaskStyles’,list)
the dialog is closed automatically with a warning that a mask parameter has been changed.
Any suggestions/ideas on how to solve this problem?
Thanks
In the Simulink “discontinuities” library, the “Saturation Dynamic” block has a button in it’s dialog, and appears to be a masked subsystem. The mask uses callbacks and initialization code. I’d like to do something similar in my own custom dialogs. Can you explain how this is done?
@Tom,
You should have a look at previous posts from Seth, there is an example that exactly address this question:
http://blogs.mathworks.com/seth/2008/08/13/dynamic-mask-dialogs/
@Tom – Buttons can not be added to user written masks using the Mask Editor. If the mask editor doesn’t provide the flexibility you need, make a GUI using M-code or GUIDE and set the OpenFcn for the block to launch your GUI.
How can I avoid the fact that mask parameters of type ‘edit’ don’t trigger the dialog callback when I return to the previous value ?
For example, I have a mask with 2 parameters ‘a’ and ‘b’ of type ‘edit’. I set a dialog callback of ‘a’ to copy the value of ‘a’ in ‘b’. First time, it works when I change ‘a’ from 0 to 1. When I come back to 0, my callback is never triggered. How can we deal with this ?
Thanks you very much
@Jack, Which release of MATLAB are you using?
I think this behavior has been modified in MATLAB R2010a and now the dialog callback is triggered also when you comeback to the original value.
If this does not behave as you expect in the latest release, I recommend contacting technical support.
Thanks for your answer,
I’m using 2006b and I do not have R2010a
Hi Seth,
I mask a C S-function and I use a mask parameter (check) to update the number of input ports in the S-function. I want to update the port labels also. When I place in the mask callbacks, I got the following warning:
Warning: Port number 2 specified in ‘port_label’ exceeds the number of input ports of ‘…’
Is there a better way to that without this warning ?
Thanks.
Is there a way to dynamically change popup menu options of a mask dialog based on parameters of the same mask while it is open and without being forced to close by MATLAB? I have a mask which has 3 parameters:
1) An edit box where I write the name of a MATLAB structure (e.g. MyStruct). This structure has a number of fields which are, in turn, structures with a number of other fields. For example I have a structure named MyStruct with:
MyStruct.Field_A = struct(‘SubField_A1′,[],’SubField_A2′,[])
MyStruct.Field_B = struct(‘SubField_B1′,[],’SubField_B2′,[])
2) A popup menu which I want to include as options the names of the fields of the structure in the first parameter (i.e., fieldnames(MyStruct) in this example);
3) A popup menu which I want to include as options the names of the sub-fields of the structure MyStruct.(FieldName), where FieldName is the field name selected in the previous popup menu (i.e. fieldnames(MyStruct.(FieldName))
I have code to do this (using the parameter callback functions of parameters 1) and 2)) but each time I maque a selection of parameter 2) that changes the contents of the options of parameter 3) MATLAB closes the mask dialog and issues the following warning:
Warning: The dialog of ‘example/Atomic Subsystem’ is being closed because a mask
parameter has been changed
Any ideas?
@Alex: The following works for me. Note the explicitly replaced delimiter, which is 124. Otherwise it won’t work, Simulink doesn’t allow that you put a ‘|’ in your code.
styles = get_param(gcb,'MaskStyles'); str = ''; files = dir('characteristics/*.m'); for f=files'; str = [str 124 f.name]; end styles{1} = ['popup(' str(2:end) ')']; set_param(gcb,'MaskStyles', styles);In this example a popup list at position 1 is created from all m-files found in a certain folder.
Regards
Thomas
hi
i am trying to change a subsystem using. edit mask/parameters.
when i use parameters and define a new one, i find out that when choose pop up type for a parameter that describes a value of a contsant block, the result of contstant block is an order number. for example when i mask a parameter ‘b’ by pop up values of 5 8 12 13 15 when i choose value as 5 output is 1, when 8 is choosed output is 2 etc.
what can i do to resolve this problem?
thanks