To use PARAMETERS or GLOBAL Variables

I want to share data values amongst Forms (I am using Forms 9i), which is a better trade-off using GLOBAL variables or PARAMETERS.
Which option is a better one ?
Please Suggest...
Regards,
Gaurav Srivastava

Also if your application uses go_form and allows the user to have two copies of the same form running at once, if you decide to use globals, make sure the form receiving the global erases it immediately on startup. Otherwise the user might go-form to the other copy of the form, which then be seeing the globals.

Similar Messages

What are Parameters? How are they differenet from Variables? Why can't we use variables for passing data from one sequnece to another? What is the advantage of using Parameters instead of Variables?

Hi All,
I am new to TestStand. Still in the process of learning it.
What are Parameters? How are they differenet from Variables? Why can't we use variables for passing data from one sequnece to another? What is the advantage of using Parameters instead of Variables?
Thanks in advance,
LaVIEWan
Solved!
Go to Solution.

Hi,
Using the Parameters is the correct method to pass data into and out of a sub sequence. You assign your data to be passed into or out of a Sequence when you are in the Edit Sequence Call dialog and in the Sequence Parameter list.
Regards
Ray Farmer

Using offset for global variables in FOX

Dear all,
I'm using global variables (i.e. defined in planning area)in my FOX formulas by using VARV-command.
I'm doing this for fiscal year, which has default value current year. However I'd like to use this variable also for next year thus creating the following code:
DATA CURYEAR TYPE 0FISCYEAR.
DATA NEXTYEAR TYPE 0FISCYEAR.
CURYEAR = VARV(Z021VA01).
NEXTYEAR = CURYEAR+1.
This gives a syntax error. Anabody any idea how I can use offset in the FOX for my variables?
Thanks in advance!
Kind regards, Harjan

Harjan,
Use TMVL function to get the offsets.
DATA CURYEAR TYPE 0FISCYEAR.
DATA NEXTYEAR TYPE 0FISCYEAR.
CURYEAR = VARV(Z021VA01).
NEXTYEAR = TMVL(CURYEAR, +1).
hope it helps.

Tables to get the hierarchy used for the global Variable

Hello,
we are using a characteristic Reporting Unit "ZCS_RDRUN" with a input ready variable "ZCS_RV_MM_REPUNITHIER_RDM".
The reporting unit is a hierarchy characteristic and the variable is a hierarchical variable of type Hierarchy node variables fixed to a hierarchy we are using for this query. We do have selected a hierarchy for the input ready variable e.g. Total Group. My question would be is it possible to read out the selected hierarchy of the input ready variable from a table? If YES, from which table? I know that we could read out all input ready variables but i dont know how to read out the hierarchy selected for the input ready variable of type "Hierarchy node variable".
I would be very thankful for all your help
Thanks and kind regards,
Muri

You check the query run times and other details in the work load analysis (ST03) or using the table RSDDSTAT .
inorder to check the information using the above two methods -make sure the Bi stats are maintained in your system
http://wiki.sdn.sap.com/wiki/display/MaxDB/WorkloadMonitor%28ST03orST03N%29

What are the best practices to use GLOBAL Variables

Hi,
Please guide how Global Variables can be declared and how they can be initialized.
Further please guide what are the impacts of Global Variables(if any) on the memory of CLIENT or SERVER, if they are not initialized or freed up after usage.
Thanks.
Regards.

spilgrim wrote:
My preference is not to use them and to use parameters or package variables. There is not real control on globals so you can end up with an applicatios that has lots of them that are only used once but persist for the user session.I second that. I don't know how often I searched for bugs caused by typos in the names of global variables. Plus the fact that they are only of datatype VARCHAR2. If you are using share_library_data you could also use Package globals in a forms library to share data between called and calling forms. Or you could use a database package...
cheers

Station global variable per UUT using a batch process model

Hi,
I have 4 UUTs which are tested using individual COM ports. I am using 4 Station Global variables to store the 4 Com ports - COM port assignments are in no particular order and vary depending on test station PC.
Example:
S1= Com12
S2= Com14
S3= Com10
S4= Com9
Using a batch process model I want to test all UUTs in parallel - I am trying to figure out what is the best/easiest way to pass S1 for UUT1, S2 for UUT2 and so on!
Any help appreciated.
Thanks & Regards,
Shane.
Solved!
Go to Solution.

The easiest way is to use the Runstate.TestSockets.MyIndex property to index an array. Each batch socket will get an index (0 to n-1, where n is the number of sockets) when it is created. Then you can create an array (of strings? I can't tell if you just have strings or need a container) and use the property to index the array.
Josh W.
Certified TestStand Architect
Formerly blue

Using built-in with global variables

I am trying to setup built-in source code control for LabVIEW. It seems to be OK except in one case:
Is it possible to use built-in with global variables ?
VIs that use a global variable are supposed to be updated automatically when global variable is modified but what happen when VIs are checked-in ? LabVIEW cannot updated them. Is it necessary to check out all VIs before modifying global variable ? This is not convenient if global variable is used in more than 100 VIs !
Is there another solution ? Can Perforce resolve this problem ?
Thanks for your help !
David

You can still use and update global variables while they are checked in to SSC. The default values will still be saved in SSC but they can still be modified and read by other vi's.
goldie

Can LabVIEW global variables be shared between UUT sequence steps in the parallel sequence model?

Sorry for this simple question, I'm having a hard time finding this answer.
If I launch a sequence to run on two UUTs in the parallel sequence module, can I get both UUTs to run LabVIEW vis that use global variables such that :
1) UUT 0 executes 20 LabVIEW Vi steps asynchronously, 5 of which access data from LabVIEW global variables A, B, C (Strings)
2) UUT 0 executes the same 20 LabVIEW based steps asynchronously 5 of which access data from then same LabVIEW global variables A, B, C (Strings)
I am a little worried that using file globals may have some delays or more of a race condition than using native LabVIEW global variables like in a single labview application perform.
QUESTION 2: Are file globals actually written to the hard drive and shared between parallel sequences through file transfer? OR are they in memory?
Brad Whaley
LabVIEW Certified Engineer

Hi bdwhaley,
Are your parallel sequences only reading from the global variable? Or are they writing to the variable as well? If it is just reading, then you should be okay. File globals are read from memory. Every time they are read, a copy of the data is made in memory.
Humphrey H.
Applications Engineer
National Instruments

Global Variable as an array

Hi All,
Culd you please tell me where I can declare a global variable as an array in PI 7.1.
In PI 7.O we used to store global variables in java sections and it was recognized across mapping in message mapping
In PI 7.1 I have declared a variable in init function in functions tab in message mapping but its not recognized in my mapping.
Could you please help me with this?
Where I have to declare a global variable so that I can use it anywhere in mapping?
Thanks in advance
Best Regards,
Harleen Kaur Chadha

Please refer to the below link about how to use global variables in PI 7.1.
/people/william.li/blog/2008/02/13/sap-pi-71-mapping-enhancements-series-using-graphical-variable
This link will help you understand how to use graphical valiable as a global variable.
Thanks,
Hetal

Functional global variable

I would like to ask to the experts a question about functional global variables.
In the labview basics 2 course was said that a functional global variable is not reentrant.
My purpose is to implement a code in such a way.2 main vi's. The first vi deals with some hardware that writes data in an output file with 1 Hz rate (more or less 1Hz, I cannot decide it).
The second vi deals with a different hardware (thermocouples). This works at a different rate (I cannot match exactly the different rates). I would like to write the data from the second hardware in the same output file of the first vi.
I am thinking to use a functional global variable to pass the information from the second vi to the first vi. In this way I am using the data from the thermocouples at a rate given by the first vi. But at the same time in the global variable the data are written at a rate given by the second vi.
My question is: what exactly happens if the subvi (functional global variable) is called exactly at the same time? As you can understand it's not really important if I read the temperature with an error of 1 second, but I would not like the execution would stop or something like that.
A functional global variable is a subVI that is not reentrant. This means that when
the subVI is called from multiple locations, the same copy of the subVI is used.
Therefore, only one call to the subVI can occur at a time.functional global variable is a subVI that is not reentrant. This means that whenthe subVI is called from multiple locations, the same copy of the subVI is used.Therefore, only one call to the subVI can occur at a time.

A couple of quick comments to add to this thread.
FG's can be involved in Race Conditions if two callers attempt to direct set the same value. An Action Engine (well what do you expect?) can be coded to help with those situations.
Example:
In arecent app I needed to set the heaters to "0" if an over-pressure condition was detected. The Heater set points where driven by a PID. The safety conditions where controlled by a process monitoring the input values.
So how do I keep the PID from setting the heater when the rig is not safe?
A Safety AE !
Actions used by the pressure monitoring set the Safety AE in an "go-safe" state where setting the heaters results in a null op.
This particular pattern (two writters) screams for an AE to coordinate the vaious actions. Do this same thing with queues could get tricky.
So for the Q in this thread we have a pattern of "two source of info, one sink for each" that screams for a queue.
BTW:
The AE Nugget linked above addresses what happens when two callers attempt to call the same non-re-entrant sub-VI.
Have fun,
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Forms personalization and global variable

Hi,
I'm trying to call a procedure in forms personalization and using a defined global variable. The data in the global variable is number. In the procedure, some of the parameter has a number datatype and I'm converting the global variable using to_number eg (to_number(:global.XX_LINE_NUM). This fails with error message ora-01403 no data found. I've tried putting the above into a variable with datatype number in the declare statement, and it errors as well.
Does anyone knows the syntax to convert the global variable to number datatype in personalization.
Thanks

Ask in this forum : OA Framework

Problems with global variable!!

Hi!
I am using some cluster (global variable), and certain fields in the cluster don't be updated.I can't understand where is the problem, because some fields are updated correctly and others no!!
Any idea?
Thanks in advanced!!
Graci

A functional global acts as a global variable in that it allows LV applications to access the data from different parts of the vi or from different vis for as long a LV is running. The vi is set to not be reentrant so that race conditions are avoided. Since functional globals are subvis that you write you also have the ability to store many global variables which are dependent upon only one input by performing the calculations within the functional global vi. You can certainly achieve this by using semaphores, but with functional globals this synchronization is built in.
In the functional global vi you have a while loop which is set to stop after 1 iteration. This while loop has a shift register which holds the global data. There is a cas
e structure to determine whether to read or write the functional global variable. In the write case the data from the input is written to the shift register on the right side. In the read case the data from the left shift register is written to the output and also passed on through to the right shift register. A good example can be found at the following link.
http://sine.ni.com/apps/we/niepd_web_display.DISPLAY_EPD4?p_guid=B45EACE3DB4956A4E034080020E74861&p_node=174821&p_submitted=N&p_rank=&p_answer=&p_source=External

How can I make my mini global variable work in more than the default case?

Hello, this seems so simple yet does not want to work. I created 2 simple read/write mini vi's and want to use them as global variables. Writing values based on a case selection. This method only seems to work in the default case. Where did I go wrong? Thanks
Attachments:
Curs 0 Y.vi ‏13 KB
Main.vi ‏19 KB
Curs 0 X.vi ‏13 KB

In case 1, you are writing to a second set of subVIs (Curs 1 X.vi vs Curs 0 X.vi). You only read from Curs 0 X.vi, and never from Curs 1 X.vi.
LabVIEW Champion . Do more with less code and in less time .

Slider - setting via global variables

Dear friends. Is there any possibility to change the "maximum value" at the slider module externally, using with the global variable?
I am programming the communication with TSA syringe pump and I need to change the range of charging rate according the used diameter of the syringe. I can prepare six different sliders for each diameter, but it is too inconvenient. Do you anybody have any idea? I tested put the variable to maximum value at the slider module field, but only a number was possible.
Solved!
Go to Solution.

What version of DASYLab are you using?
My slider module with DASYLab 12 allows a Global Variable for the Min and Max, and it changes while running.
One way to tell if a Global Variable is supported... right click in the parameter field.
- cj
Measurement Computing (MCC) has free technical support. Visit www.mccdaq.com and click on the "Support" tab for all support options, including DASYLab.

Use global variable in reports which is declared in forms

Hi All,
I have declared and used a global variable in Forms and after that I'm running a report and I want to use the same variable in reports.
How can I use that.
Regards
Praveen Kr. Arora

Hi Rizwan,
Thanks for prompt reply.
Can you explain in more detail with example.
Though I'm calling report from menu item and I have created report file with three parameters.
In menu item I have created a parameter list with same three parameters but whenever I tried to run then it gives Invalid ID error for all three parameters.
Regards
Praveen Kr. Arora

To use PARAMETERS or GLOBAL Variables

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