What DCB should be for PCI-8433 RS-485 serial card???

[serratus]

Hello everybody,

I have a PCI-8433 RS-485 serial card.

I install the card and operate the "Trouble Shooting Wizard" and all the 4 channels passed the test.

I want to use one of the ports of the serial card in RS-485 2-wire auto mode.

Although in my company we have all MeasurementStudio components of NI, I want to use basic Windows functions like CreateFile, ReadFile, GetCommState etc. etc. etc.

By using "Measurement and Automation Explorer" I set the baud rate to 115.2 KHz, 8 data bits, Odd Parity, 1 stop bit and RS485 2 wire auto mode.

When I open "Measurement and Automation Explorer" and press the "Communicate with serial port" button and try to receive some data, I could not manage it. (I do send RS-485 data and observed the data bits by a scope. RS-485 signal levels and really 115.2 kbits/sec)

Then I wrote some code by myself (for PCI8433 card) and check the DCB structure of the port I am using. My code sample and the DCB structure result is in the attached text file:

QUESTION1:

In RS485 auto mode; "should fParity be TRUE", "should dDtrControl be TRUE", "should fRtsControl be TRUE"as they have the value "1"?

QUESTION2:

Is it necessary to change the above items in the DCB structure and do I have to change anything else???

Thank you

Have a nice day!!!

[Roland A.]

Hello Serratus:

Thank you for contacting National Instruments. To answer your questions, it is up to the user to decided on which settings he/she wants. You do not need to change anything if you are okay with the default settings.