Addressing single bit

[dingin]

hi everyone

I am working with datasocket and OPC server. The data comes in 2 forms,

a 32 bit float and single bit.

I can read and send the 32 bit tag by using the numeric

data type single precision, but as for the single bit, the smallest numeric

data type LV has is 1 byte.

The OPC explorer program allows me to address the entire byte or each bit

which represent valve on/off states. In LabView I just want to be able

to address a particular bit, not the entire byte.

Any suggestions would be greatly appreciated!

[LAVA 1.0 Content]

Any suggestions would be greatly appreciated!

As far as I know the smallest addressable memory element in C++ is one byte i.e. 8-bits. If your OPC interface uses something like 1 bit variables, they very probably are really 8-bit variables of which only 1-bit is used. Can you provide the defenition of the OPC method API you are trying to pass bits and how these bits are defined in the API.

[dswaine]

...

I am working with datasocket and OPC server. ...

In LabView I just want to be able to address a particular bit, not the entire byte.

Any suggestions would be greatly appreciated!

Apologies if I'm missing something but ...

If you're using frontpanel Datasocket connections: have you tried just linking a boolean/switch to a particular bit?

If you're using the Datasocket VIs: have you tried DataSocket Write Boolean.vi or DataSocket Read Boolean.vi (from ... \LabVIEW xx\vi.lib\platform\dataskt.llb).

[Louis Manfredi]

Hi Dingin:

Welcome to LAVA :thumbup:

Although you may be forced to pass your boolean data around as eight bit bytes, you certainly can break it into booleans using LV.

See below for a couple of may ways...

Hope this helps, Best Regards, Louis

[Omar Mussa]

A 1-bit number simply means its value can be 0 or 1. And luckily enough, a rose is a rose... If you use any of the int type of data and send a 0 or 1 your code should work. Reads and Writes to that value shouldn't require any 'bit banging' because the value is just 0 or 1 (there is nothing to manipulate).

[dingin]

:worship:

I tried each of the suggested methods, and they all work!

-Using front Panel Datasocket connection to OPC,

1) write a True or False to boolean control (V3.1,3.2 in my example)

2) send 0 or 1 to I8 unsigned byte (V4.1,4.2, in my example)

3) convert 8 element 1D boolean array (with boolean array to number function) and pass to I8 unsigned byte.

-In the block diagram

3)Use a datasocket write boolean subVi from dataskt.llb (V6 in my example).

I had tried the boolean and I8 in the front panel DS connection before without success.

My OPC server must have hosed up somehow on that occasion.

Thanks everyone!