RS232 & EVAL-AD5764EB

[Bulatov]

Hi everyone!

I'm woking with evalboard EVAL-AD5764EB from Analog Devices. I connected it with my PC by RS232.
Data is written to the evalboard in a 24-bit word format. I try to solve this task by using VISA,
but each data-bit from 24-bit word written to evalboard in ACSII format and nothing work.

How I can send 24-bit word from PC by RS232 in non-ACSII format? 

[Dennis_Knutson]

One way is with the Byte Array to String function. Another is to right click on your string control/constant and select 'Hex Display'. 

Message Edited by Dennis Knutson on 03-25-2009 11:34 AM

[Bulatov]

When I send data in string format each bit from 24-bit word converted in ASCII and then new code of bit sends into port, but  i need organize serial of bits (24-bit) on Tx pin of RS232 (COM). Each bit will gather in shift register in evalboard. 

[Dennis_Knutson]

You send ASCII if your string control/constant is set for normal display. Using the methods I mentioned, there is no conversion into ASCII.

Does the board ignore the start and stop bits and just use the data bits so that it gets 3 packets that are each 8 bits long or does it require you to cotnrol the start and stop bits as well? If it's the latter, I'm not sure how you can use the standard com port functions in LabVIEW.

[Bulatov]

I forgot about stop/parity bits!!! So i cannot use VISA/Serial. How I can work with COM port without this function and get full control under Tx and Rx pins?

[Dennis_Knutson]

I don't think you can use the RS-232 port. I had a quick look at the specs of the board and it seems the serial interface is SPI. The voltage levels of a RS-232 port are not correct. NI sells the USB-8451 for that.

[Bulatov]

Evalboard have integrated USB controller, but USB not supported in LabVIEW Real-Time, that's why we choose to use RS232 to communicate with evalboard, but you say, that we cannot use it. Maybe exist some controller, device or program module, which can communicate with evalboard under Real-Time using SPI? 

Message Edited by Silentium on 03-25-2009 02:37 PM

Message Edited by Silentium on 03-25-2009 02:39 PM

Message Edited by Silentium on 03-25-2009 02:40 PM

[Bulatov]

We will use logic-level converter based on MAX232. But how I can get full control under COM-port and send data continuously (without any system commands)?

[Dennis_Knutson]

As I already said, I don't believe you can avoid the start/stop/parity bits. They are automatically added by the UART. Instead, maybe you could use the parallel port or some digital I/O board.

[Bulatov]

We have an idea. Can we take *.dll for USB from Windows, write code under ETS (for real time) which can call this *.dll (dll in Windows almost same like in ETS) and work with USB in Real-Time? All we need it's work with this evalboard in Real-Time and how we can do this without buying additional devises (like NI8451)!