Hi,
I am working with a NI 9871 (serial RS485) an I seems to have a problem with sending a command to a instrument.
The instrument is connected to the NI 9871 with 2 wires, which is connected to pin 4 og 8(+) and pin 5 og 9(-) on a DB-9 connector. Is this a 2 wire connect or 4 wire? I ask because when I sent a sing to the port on the NI9871 I get the same string back if I use 4 wire mode but nothing if I use 2 wire mode.
This instrument needs a 4 letter ASCII string and will return a long string with data. In order for the instrument to recognizes that a command is being sent it needs a break signal. The instrument manual says this about the break signal:
“The break Signal suspends the character’s transmission on the serial line, setting it to a break status. In this status, the voltage level of the transmission line from the computer to the Anemometer passes from nominal -12V to +12V. “
Does Labview sent this kind of break signal?
-gjels
