01-13-2007 09:08 AM
01-13-2007 09:34 AM
01-13-2007 10:17 AM
01-13-2007 01:57 PM
The pic is placed on an ICD programmable board and program is downloaded easily to pic using a software. The minimum acquisition time is 19.72μs; A/D conversion time is 19.2μs, A/D sample time is 38.92μs.10 bit A/D result will be loaded to both ADRESH and ADRESL registers but 8 bit data in ADRESH will be transmitted wireless to the receiver module. If using RS232 to input data to my PC, an additional chip to boost the signal level up to +/-15V is needed and this is a bit troublesome to me (correct me if I am wrong). So is it possible to display my receiving data in a waveform chart by just using USB6009 and Labview? Hope to hear from you soon. 🙂
01-13-2007 02:40 PM
01-13-2007 04:07 PM
Okay, that's a little better.
You will never be able to read the output of a serial port with the USB-6009. For one thing, it's too slow. Even at 9600 baud, you won't be able to keep up. The USB-6009 has software timed digital I/O. You can only read a single bit at a time and a 9600 baud rate means an entire byte (8 bits) is transmitted at that rate. Second, even if you could read at the desired rate, you couldn't synch up. You would have to be able to know which bit is which part of which byte is being transmitted and even if add code to determine start bit, data, stop bit, etc. that would just slow down the digital I/O even more. It would appear that you have to use the pc's serial port though I really am not sure you can keep up with the A/D conversion. If the signal levels are not RS-232, what are they? If you could get the data with a serial read, it is easily converted to a format that can be displayed on a graph or chart. That just requires a type cast or the string to byte array function.
01-13-2007 04:56 PM
So as what you have mentioned, I have to use usb-to-rs232 to input the data bytes to my PC. Does you mean that I have to extract data from start bit and stop bit? Could you give some advice on the proper steps of display digital signal on graph by using rs232? what should be take note of when using rs232? I am really not familiar with Labview therefore I will definitely need to have a lot of reading.
Thank you for your help and I hope to hear from you soon.
01-13-2007 05:30 PM - edited 01-13-2007 05:30 PM
No, you don't have to extract anything. Your pc's uart will do all of that. all that you would have to do is read one byte at a time. This is all done with the VISA functions. The string returned would be converted to a U8. In the example below, I use the type cast to do that. Then, If you want a floating point number displayed, you multiply the U8 by the bit value . The bit value is the full scale voltage range of the A/D divided by the total number of bits that the A/D has (i.e. 2**12).
Message Edited by Dennis Knutson on 01-13-2007 04:31 PM