Tty / 20 Ma Current Loop (X3-Ser1); Pin Assignment; Fig. 7-3: 25 Pin D-Sub Female Connector Strip; Fig. 7-4: Pin Assignment Tty / 20 Ma, Passive - Bosch Rexroth IndraControl VCP 25 Project Planning Manual

7-4 Bosch Rexroth AG | Electric Drives and Controls
Interfaces
7.1.1

TTY / 20 mA Current Loop (X3-SER1)

7.1.1.1 Pin Assignment

Depending on the wiring, it is possible to connect the interface either as
an active or passive current loop. The transmit line and the receive line
are each provided with a separate 20 mA power source. The compli-
ance voltage is approx. 24 VDC.
The 20 mA power should be supplied by the transmitter unit. This
decreases crosstalk on the signal lines considerably.
In idle state (signal logic 1), a 20 mA current loop can be measured in
the cable.
Signal Logic 1 Current Flow 20 mA
Signal Logic 0 Current Flow Interrupted

Fig. 7-3: 25 pin D-SUB female connector strip

Connector in the small operator terminal: 25-pin D-SUB female con-
nector strip
Pin Designation Function
10 T+ Transmitted Data, Positive Polarity
13 R+ Received Data, Positive Polarity
14 R- Received Data, Negative Polarity
19 T- Transmitted Data, Negative Polarity

Fig. 7-4: Pin assignment TTY / 20 mA, passive

Rexroth IndraControl VCP 25 | R911299720 / 02