topic Re: declare labview data word in LabVIEW

declare labview data word

huikim — Mon, 02 Jul 2012 08:28:51 GMT

Hi there,

I am a new user on labview. Previously a PLC programmer.

I wish to know or is there a sample program for the steps below.

1) declare a local word variable

2) use (read & write) individual bit from the word for programming

adrian

Re: declare labview data word

danil33 — Mon, 02 Jul 2012 08:32:55 GMT

Hi huikim,

what you are trying to achieve is,you are entering a word into a string control and after running the VI you have to display it in an indicator.Is it??

Re: declare labview data word

huikim — Mon, 02 Jul 2012 08:55:26 GMT

hi danil33,

would like to individually change the bit status of a word variable.

example, first i need to create a word variable. The i want to change the bit3 of the word from 0 to 1. i.e. 1 word =8bits i.e. bit7, bit 6,.... bit1, bit0.

How can i create the local word & change the status of the bit?

Re: declare labview data word

danil33 — Mon, 02 Jul 2012 09:06:53 GMT

Hi huikim,

From your explanation I think you are trying to achieve this.If not please tell.

Re: declare labview data word

huikim — Mon, 02 Jul 2012 09:20:24 GMT

Hi Danil33,

It's not what i actually wanted but thanks for the support anyway. i'll try to figure it out first.

Thank you

Re: declare labview data word

smercurio_fc — Mon, 02 Jul 2012 13:28:30 GMT

@huikim wrote:

Hi there,

I am a new user on labview. Previously a PLC programmer.

I wish to know or is there a sample program for the steps below.

1) declare a local word variable

There are no variables in LabVIEW. While you can create "local variables", they are a misnomer. They are actually more like shadow copies of front panel controls/indicators. You can create constants. Perhaps this is what you are looking for.

2) use (read & write) individual bit from the word for programming

Boolean functions can be used to do this. They can operate on integers just as well as Booleans. For example, if you have an integer datatype, like an I8 (8-bit integer). You can find out if the 3rd bit is set by simply ANDing it with the value of 4 and seeing if the result is greater than zero (if you want a Boolean yes/no).

To set a bit you'd OR with the appropriate mask (i.e., a mask that has only a 1 at the position you want to set and everything else a 0).

To clear a bit you'd AND with the appropriate mask (i.e., a mask that has a 0 at the position you want to clear and everything else a 1).

Re: declare labview data word

huikim — Wed, 04 Jul 2012 05:46:08 GMT

Thanks for the information, smercurio_fc

I also thought of this method & will try to play around with LabView.

One more request. Do you have the instruction list for LabView. List each instruction/module with details desciption & function?

Re: declare labview data word

GerdW — Wed, 04 Jul 2012 07:36:31 GMT

Hi huikim,

there's the great context help, also available as online help...

Re: declare labview data word

crossrulz — Wed, 04 Jul 2012 13:48:19 GMT

Since it sounds like you are very new to LabVIEW, you might want to look at some of the online tutorials.