Rs232 , although i can perform a loop back on bit 2 and 3 i can not read back data with the hardware i am using , any suggestion?

[Doran]

Hello ,

I took the Basic serial write and read vi , from ni examples .

I started with  loop back on bit 2 and 3 as described in description , this loop works. 

The problem is , that while i am connecting my hardware and trying to perform operations that work on telnet ,

In the LV (8.5)  i can not read back data with the HW  ,I tried to change rate, and baud rate but it did not helped ,

Please is there  any suggestion?

Thanks

Doran

[nitad54448]

hi

in my opinion, the most common error with RS232 -I've done that- is that the hardware is not responding. Ususally is the cable (serial, null modem etc..), that means : what is a TX for the other should be the RX (but not always !).

If the vi you mention is working then is a good point. Now, you have to be sure that the TX on the cable connects to the right pin to the hardware (try changing the cables first, then if it is still not working post again...)

N

[Dennis_Knutson]

The loopback test verifies that the UART on your pc is working and that you have NI-VISA installed. It doesn't do much more than that. With a instrument connected, the things that could be wrong are: wrong baud rate, wrong parity, wrong number of stop bits, wrong number of data bits, wrong number of stop bits, incorrect command, incorrect format of command, straight through cable when null mom is required, null modem cable when straight through is required, no termination character, incorrect termination character, incorrect format for termination character.

There are so many things that could be wrong and you haven't provided much information as to narrow it down. You could provide the make and model of the instrument, the exact command you are sending, the programming manual, and the actual VI with the command saved (use Edit>Make Current Values Default). I would also recomend using a program such as Hyperterminal first. You can usually get help from the vendor if you explain what you have done with that. Some will have never heard of LabVIEW.