I have spent a great deal of effort trying to find answers to these questions. Formal language reference information for VBScript, both on the Microsoft website and on this website, seems to be cursory at best. Before I get into any detailed, complex explanations of exactly what I am trying to achieve, let me start with two very simple questions, requiring yes or no answers, which I have been unable to resolve.

1.   Is it possible to pass a string as a parameter to a user defined function?

2.   Is it possible to pass an object reference as a parameter to a user defined function?

I suppose, if the answer to either of those questions is yes, then a simple example of how to do it would progress the issue for me. A generic example of what did not work for me would be:

Sub <functionname> (ByRef ScreenName)

    HmiRuntime.Screens(ScreenName).ScreenItems(<itemname>).<property> = <property setting>

End Sub

The function call ScreenName parameter was set to a string type and the value was a valid screen name enclosed in quotation marks.

Any help greatly appreciated. Direction to the comprehensive formal language reference, if it exists, would also be appreciated.

Ken

Dear KenNatton,

do you use a panel or RT Advanced/ Professional? On a Panel there is Windows CE running. In Windows CE you have not the full functionality as in e.g. RT Advanced.

Do you know the programming references for VBS?

https://support.industry.siemens.com/cs/ww/en/view/109747176
https://support.industry.siemens.com/cs/ww/en/view/109747179
https://support.industry.siemens.com/cs/ww/en/view/109747940
https://support.industry.siemens.com/cs/ww/en/view/109747968

With best regards

rh1990

Dear rh1990

Many thanks for the reply. I had done some extensive searching for documentation and had found some similar to the ones you have linked to above, but none exactly the same. I don’t know why I did not find these. I confess that I am a little concerned that they are described as print-outs of the on-line help, because I did search the on-line help and did not find what I was looking for, but I will review these documents, perhaps I will find them to be better.

I am using a Comfort panel, and I am using the basic version of TIA Portal V14 SP1 – the hardware we use is all S7-1200, we never need to go to S7-1500 – but I do have the WinCC add-on required for the programming of Comfort panels.

I have to tell you, at this point, I have actually given up on what I was trying to achieve. Because I could not pass the parameters I needed I simply had to write seven different versions of essentially the same script. But what is strange is, those scripts worked perfectly in simulation, but they do not work when downloaded to the actual HMI. I put in a diagnostic variable write that proves the script is being called. But it doesn’t seem to execute properly. For example, within the script I have a For Next loop that should iterate 16 times. I put another diagnostic variable write to count the iterations of the For Next loop and it comes back with a zero. I have absolutely no idea why.

So I have had to achieve my main aim a completely different way. Essentially, I am butting up against the 2048 tag limit. These scripts were an attempt to reduce the tag count by reading groups of Booleans as an integer value. Instead, I have reduced my tag count by mapping groups of values into arrays and passing those up to the HMI in a single tag. Not ideal, but the best I could do.

Best regards

Ken

Not sure if I am talking to myself here, but just in case…

Having checked out the documents that rh1990 provided links to, they do have exactly the same problem as the other documents I had found. There is fairly detailed information about system functions and about the object model. Which is great if what you want to do is use system functions or refer to objects within your scripts. But they do not give any language reference information at all. For example, I have gathered that if you declare any local variables within your VBscripts, you cannot specify a datatype for the local variable. They are all, it would seem, necessarily variants. But I have gathered that information from experience because I can’t find anything anywhere clearly stating that to be the case. Now I get it that that side of things may not actually be Siemens. VBScript is defined by Microsoft and there is information about VBScript on the MSDN website. But even there, while there is some cursory information about passing parameters to functions, there is no exhaustive reference information either stating that you cannot pass a string as a function parameter, or demonstrating the technique for doing so, and either stating that you cannot pass an object variable as a function parameter or demonstrating the technique for doing that. And my attempts to guess at the technique have not worked. So I am left having to assume that you can’t. Unless anyone out there knows any different…

KenNatton

Not sure if I am talking to myself here, but just in case…

...

 In VBS you cannot speficy the datatype of a variable. Datatypes are assigned automatically.

@Edit.

To answer your questions:

Ad.1) Yes, it is possible to pass a string as a function parameter. I don't see why you would have any problem with this.

Ad.2) About object reference as a parameter - I'm not sure to be honest, but even if it's not possible to do directly, you can always transfer it as a string to the function, and then use in VBS commands. At least that's how I imagine it would work.

Nattana

  Ad.1) Yes, it is possible to pass a string as a function parameter. I don't see why you would have any problem with this.

 Well, the reason I have a problem with it is because it didn’t work. And simply stating that it is possible doesn’t help me if you don’t either demonstrate the technique for doing so or direct me to specific documentation that demonstrates the technique.

Okay, let me try and lay it out for you. I wanted to write a script that could be used to refer to similar screen items on different screens. So the string I wanted to pass into the script as a parameter was the screen name. The intention was when the script call was defined, you could specify the screen name that it applied to at that point. If I included a line that named the screen directly in the script, it worked. So clearly I had the syntax correct. But as soon as I tried to replace that with a parameter name and specify the screen name as the parameter, it didn’t work. In the past, with other languages, when I have experienced problems like that, it has usually turned out to be some subtle nuance of the technique that wasn’t quite right, and the place where you find the solution is either in the detailed formal language reference or by looking at examples that actually work. That is what I can’t find and thus can’t resolve my problem.

KenNatton

 Well, the reason I have a problem with it is because it didn’t work. And simply stating that it is possible doesn’t help me if you don’t either demonstrate the technique for doing so or direct me to specific documentation that demonstrates the technique.

Okay, let me try and lay it out for you. I wanted to write a script that could be used to refer to similar screen items on different screens. So the string I wanted to pass into the script as a parameter was the screen name. The intention was when the script call was defined, you could specify the screen name that it applied to at that point. If I included a line that named the screen directly in the script, it worked. So clearly I had the syntax correct. But as soon as I tried to replace that with a parameter name and specify the screen name as the parameter, it didn’t work. In the past, with other languages, when I have experienced problems like that, it has usually turned out to be some subtle nuance of the technique that wasn’t quite right, and the place where you find the solution is either in the detailed formal language reference or by looking at examples that actually work. That is what I can’t find and thus can’t resolve my problem.

 Hmm. Could you post an example of a script/functions with a string parameter that you tried and didn't work? Also, have you tried displaying the content of your parameter in an I/O field to check if the screen name it contains is passed correctly?

Kind regards,
Nattana

Nattana

  Hmm. Could you post an example of a script/functions with a string parameter that you tried and didn't work? Also, have you tried displaying the content of your parameter in an I/O field to check if the screen name it contains is passed correctly?

Kind regards,
Nattana

Sorry Nattana, my best attempts to portray the story directly in the post were defeated. The best I could do was put it in a word document and attach it. Hopefully, the attached does tell the full story.

Best regards

Ken

Hi Ken,

when you want to give over "Home" as string, you have to select String as type of the input when calling the script. When you call the script on value change, you can select the type on the right end of the input field where you entered "Home".

Best regards,

Frink

Prof. Frink

Hi Ken,

when you want to give over "Home" as string, you have to select String as type of the input when calling the script. When you call the script on value change, you can select the type on the right end of the input field where you entered "Home".

Best regards,

Frink

 Hi Frink,

yes, I did that. If you don't do that then you cannot enter a string as the value of the parameter in the script call.

Best regards

Ken