Current Loop; Setting The Current Sources; Fig. 8-12: Rs 485 Cabling For Serial Port 2 - Addi-Data ADDICOM PA 7400 Series Technical Description

Technical description

8.3.4 Current loop

You can operate serial ports 1 and 2 like current loop ports.
You can receive and send actively as well as passively.
There is for each mode, transmission and reception, one 20 mA current loop
source.
•
Make sure that the setting corresponds to the peripheral current loop.

Setting the current sources

Active mode:
The current sources of the board deliver the necessary 20mA current loop on the
receive and transmit line.
Passive mode:
The current sources of the peripheral deliver the necessary 20mA current loop on
the receive and transmit line.
According to the configuration the mode is set as an active
transmission/reception or a passive transmission/reception.
•
Select the current sources:
with jumper J22(3) (transmit line)
with jumper J23(4) (receive line).
Chapter 8

Fig. 8-12: RS 485 cabling for serial port 2

PA 7400
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