I have a signal on RS232 but i have to take it on a RT card

[Anthares]

"hello

I have a signal on RS232 but i have to take it on a RT card (7030/6040) because i don't want to pass through operative system and pc...i can't use an analog signal instead rs232 because i have noise problem on a slip-ring carrying the signal.


So i figured to attach cables of RS232 on the DAQ board, but some people said to me that is not possible to syncronize and buffer digitals I/O to recreate the serial protocol/transmission.
I 'd like to execute all my algorithm on the RT card, but if i can't reach to connect this serial signal on it i will be forced to use the pc for part of the algorithm, could u help me?


Has anyone of you ever connected the cables of a serial interface
on a DAQ board?


Thank you.


Anthares"

[Chad_H]

RS-232 and National Instruments digital I/O are not meant to be compatible. One problem is the voltage level, although this can be resolved. The RS-232 bus uses approximately -12 volts for High Logic, and +10 volts for Low Logic, not 5 to 0 volts. Another problem is mimicking the RS-232 protocol with hardware and software. I don't know how you would do it, if you could do it.

If you want to access serial a serial port directly from a Real-Time program, you can run it on an RT Series PXI Controller, which has serial ports. Remember that serial communication is not deterministic.

When using the PCI-7030, you will need to access the serial ports on your PC with a VI running targeted to the host, and transfer that data to the RT Engine VI on the 7030 using shared mem
ory or TCP/IP.

Chad Humberstone
Application Engineering
National Instruments

[Anthares]

Thank you Chad.

I' m considering problems about this kind of connection, and i think i'll use serial port on pc, i would not want to use host pc for another problem.
I have three different interfaces (vis) talking with the RT engine, but i noticed that if i start RT engine and one of interfaces all is ok.
But when I end the host vi changing another interface the shared memory doesn't resynchronize.
National said to me that killing a host vi using target memory and recalling it is not possible, due to byte controls used by sharing memory system.

So i am going to try tcp/ip to connect different Vis, or a Vi server to make communications between interface (A) and serial acquisition (B) on host pc and shared memory between B and Rt engine....but i think that tcp/ip coul
d be the better way for this problem.

Thanx