Technical data

46 Connect Devices WAGO-I/O-SYSTEM 750
750-652 Serial Interface RS-232 / RS-485
Manual
Version 1.3.0
Figure 14: Bus Connection RS-485 Operating Mode with Biasing Network, Half-Duplex
With the use of the biasing resistors, it is guaranteed in this case that all receiver
inputs A have the voltage difference of more than 200 mV to the inputs B if no
transmitter is active. The oscillations of the receiver that can cause defective
reception are thus prevented.
Biasing network
Check the necessity of an external biasing network before start-up.
In modern devices with RS-485/RS-422 interface, this network is either already
integrated or the devices have an improved RS-485/RS-422 receiver. The output
of this receiver is in a defined state if the data line is short-circuited or not active.