JUMO 705001 mTRON T - Central Processing Unit Operating Manual - Manual (Page 29)

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4 Electrical connection
4.3.4 Terminating resistors
The internal terminating resistors for the Com1 and Com2 interfaces are only relevant for
RS422/485.
The terminating resistors are deactivated by default. To activate them, DIP switches 1 to 4 for
the relevant interface must be pushed upward using a suitable tool such as a ballpoint pen (ON
position).
The following figure shows the position of the DIP switches when the terminating resistors are
activated.
Internal terminating resistors
2 1 3 4
ON
NOTE!
To ensure fault-free operation, terminating resistors are required at the start and end of an
RS422/485 transmission path.
332
?
120
?
332
?
GND
+5 V
4
9
332
?
120
?
332
?
GND
+5 V
3
4
3
8
1
2