How do I power an RS232-port device through a DAQ device?

[Dennis Knutson]

Do I understand you correctly? You are trying to acquire data from an RS-232 device with a DAQ board? Powering the port is going to be the least of your problems. One, the voltage levels of RS-232 are not compatible with the TTL levels of the digital I/O of any NI DAQ board. Two, the timing requirements of RS-232 would require you do a lot of custom programming. That's if the digital I/O of the DAQ device is even capable of it. You don't mention which board you are using. If it's got static ditial I/O, forget about it. Even if you had power to the serial instrument, MAX would not recognize a serial device and neither would Signal Express.
A USB->RS-232 converter is pretty cheap. I've seen them range from $15-$25.

[Dennis Knutson]

I've not used Signal Express. You can check the answer by Ebele in <a href="http://forums.ni.com/ni/board/message?board.id=140&message.id=23559#M23559" target="_blank">this post</a> for information on how to create a custom step in LabVIEW and import it into Signal Express. You might have to do this for your serial instrument.

The voltage measurement with the 6211 should be very straight forward.