ni 8431 output voltage

[Giladbil]

hi,

I am using ni 8431 serial board for rs-485.

when i login windows there is a constant output voltage on TX+ line.

how can i disable the output voltage and activate it again after certain setup on my UUT ?

regards

gilad

[Misbahd]

In the case of NI 843x RS-232 devices, the voltage output signal level is of +/-5.5 volt logic. Moreover, +5.5 volts represents a logic low and -5.5 volts represents a logic high. These output levels cannot be changed.  

See https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YFtECAW&l=en-US for more info.