What is the threshold for a logic low and what's the threshold for a logic high in the RS485 communication?

[GaryZ21]

I am using CVI to command the PCI RS485 / 8 port card. 

What is the threshold for a logic low and what's the threshold for a logic high in the RS485 communication?

[MissyS]

Hi,

The RS485 communication is differential, not a single-ended voltage. Based on this link, the RS-485 voltage signal ranges from -7 to +12 V. If the negative line is less than the positive, this is a 1 or MARK. If the negative line is greater than the positive, then this is a 0 or SPACE.

I hope this helps!

Regards,