Hello,
Im trying to check if my USB to serial RS485 converter (Digitus- DA-70157 FT232RL based) is working. When i used RS232 i could perform simple loopback test in Realterm/hyperterminal/Br@y++ Terminal
I read that something like this is not possible with RS485? I found example at NI site
http://digital.ni.com/public.nsf/allkb/D5CC369B3E3E6F0586256D1600563245
Im looking at "Two-wire Echo (non-Auto) Mode"
I connected my USB to serial converter to USB (using latest FTDI drivers 2.12.0.0, i can see new USB serial port in device manager under COM3). I prepared a loopback connector just like in article above (both socket and plug pins are numbered so i double checked they are right, i also tested connectors to see if singal can pass).
I downloaded VI attached to article above. Fresh from the page, no modifications. I open it (lab view 14.01 32bit and i downloaded what seems to be newest Ni Visa drivers from October 2014 http://www.ni.com/download/ni-visa-14.0.1/5023/en/ my operating system is windows 8.1 64 bit)
Then i configure Visa serial connection to match settings in device manager:
Baud rate 9600
data bits 8
parity none
stop bits 1
flow control none
delay before read 500
And of course most important i pick Visa resource name COM3 (i checked it against my device manager and USB to serial convered does indeed appear under COM3)
I type in string to write "test" and..... no matter what i do it ends up with error:
"Error -1073807330 occurred at Property Node (arg 1) in 485 Loopback Test 2 Wire Echo.vi
Possible reason(s):
VISA: (Hex 0xBFFF001E) The specified state of the attribute is not valid, or is not supported as defined by the resource."
It happens if write is On and read is Off. It also happens if write is Off and read is On and happens when both read and write are off aswell. It also happens if the string to write is default "*IDN?\r\n"
The only thing i figured out is that if i delete first property node "wire mode" the progam will execute without errors but i seems that it does nothing, string to read is empty.
The exact same thing was happening at other computer (with older labview and older ni-visa drivers) and i thought its because of not up to date drivers thats why i tried other computer with stuff that is up to date.
I did thing you do every time something goes wrong:
- i tried unplugging and plugging converter again,
- i checked other USB ports and i tried plugging converter directly into USB (no additional cables)
- i tried restarting my computer and labview
and the error above still haunts me.