Siemens SIMATIC CP 440 Manual page 77

Initial State of the Receive Line
Figure 5-1 shows the wiring of the recipient at the X27 (RS 422/ 485) interface:
none
R(A)5V/R(B)0V
R(A)0V/R(B)5V
Figure 5-1
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
Wiring of the Recipient at the X27 (RS 422/485) Interface (ASCII Driver)
Configuring and Parameterizing the CP 440
0 V
5 V
5 V
0 V
R(B) +
R(A) –
R(B) +
R(A) –
R(B) +
R(A) –
5-13