Conversion of binary to number

Question

Hello,
I have a signal conditioner controlled through serial communication with ASCII commands. Once the start command is received, there is a continuous stream of offset binary data sent and read through the serial Read Indicator. The manual informs me that I must first condition the offset binary values by subtracting 2048 from the raw values to produce a 2's complement value,  it also mentions that the data is encoded in 12 bits so negative numbers must be properly sign extended to move the data into 16 bit words used by the PC. I am not familiar with binary numbers and am unsure on where to start. If someone could provide some insight and suggestions on what my first step would be to converting the binary values into number format, that would be greatly appreciated.
Thank you in advance,
Jena

Answer 1

That won't work because he's not receiving the string the way you think it is. The hex display is an interpretation of the underlying byte values. It is not the same as number written out in hex as a string. Your conversion assumes he's getting the character 1, followed by the character 8, followed by the character 0, followed by the character 0, followed by a space character.
The simplest way is to use the Type Cast function, 'cause that's what it's there for. Wire in an array of the datatype you want. The thing to keep in mind is that even though the data may be fundamentally 12 bits you need to deal with multiples of 8 because a serial read will read bytes, not bits. Thus, you can convert your string to an array of I16 numbers like this:
Message Edited by smercurio_fc on 04-08-2008 01:07 PM
Attachments:
Example_VI_BD2.png ‏2 KB