Can I send RS232 data bytes through PCI-8431/8 NI cards, I use CVI software 8.5.1 with theses cards? Thank you for helps.

[Dev00]

HI

I'm using PCI-8431/8 NI cards to read RS485 databytes received from another emitter host.

But when i communicate with this host, i have to send RS232 data bytes to it (in other hand of this host it will send rs485 that i will read by 8431).

I think to use my PCI-8431 to send RS232 data bytes required by this host. I use CVI software 8.5.1 with theses cards?

Is this possible? Is developping CVI function or module or other API (DLL or other) is needed to do thus?

I need help and information. 

Thank you in advance.

[Dennis_Knutson]

That does not make any sense to me. Are you saying that the receipt of data from the instrument is a physical and electrical RS232 interface but the transmit of data is a physical and electrical RS485 interface. Two separate interfaces?

Attach the instrument manual.

[Dev00]

I didn't well explain the pblm.

I'm communicating from a PC with an external board PCBX that's only receive RS232 data and it sends RS485,    SO, I have to send RS232 to PCBX and respectively read RS485  :  SO, I installed in my PC the PCI-8431 NI card to communicate with PCBX, I use this card well to read from PCBX outcoming data to the PCI-8431 but, I think to use it (PCI card) in the same time to send RS232 (converted to TTL) to PCBX. PCBX in himself has two modules Emiss in RS485 and Receip in TTL/RS232.

Implicitly, i have an interface of conversion RS232/TTL.    

Thank you for your help.

[Dennis_Knutson]

The difference between RS485 and RS232 is electrical. RS485 is differential and RS232 is not. I's a bit confused about your answer but if you have separate connectors, just plug the RS232 connection into a standard pc port (or a USB-RS232) and the RS485 into the NI card. One VISA resource name for writing and a different for reading.

ps. RS232 and TTL are not at all the same either.

[Dev00]

What you say is very logic,

But in fact I haven't COM port or suffisant number COM ports, So i thought to exploit work with my PCI-8431/8 to send theses RS232 data bytes (even by CVI library functions or other soft solution : dlls, developping some modules or drivers, ...

I ask essentially about PCI-8431/8 card features? : is it compatible RS232/RS485 PCI card??? can i configure it to extend its role, even by soft?...

Please accept my great thanks.

Best regards. 

[Dennis_Knutson]

You keep talking about RS232 data bytes and there is no difference in RS232 or RS485 DATA! The difference is electrical and you would need to convert the differential signals from the RS485 board to the single ended RS232. As far as I know, the 8431 does not support RS232. Converters are readily available so make a custom cable assembly. USB-RS232 converts are also readily available and there's generally no reason you can't have as many as you want in your pc.

An instrument that can only send data in one format and only read data in a different format is very odd. I would still like to see the manual. could you at least provide the make and model?