KROHNE CORIMASS MFC 85 Interface EN - Manual (Page 13)

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3. Connection of instruments on the Bus system
The following terminals are used in the MFC 081/085 converters for the signal receive (Rx),
transmission (Tx) and ground.
3.1 Single Master/Slave configuration (Non Ex applications only)
4 TX-/RX-
TX/RX
TX/RX
4.1 TX+/RX+
Terminating
Resistor
120R 120R
screen
Screened twisted pair cable
MFC 081/085
rear terminal
compartment
Fig. 1
Notes:
1. Terminating resistors to be used at both ends.
2. Terminating resistors to be mounted externally between terminals 4 and 4.1 if not
internally connected.
3. For Ex instruments the terminating resistors must be internally connected. (See section
below).
3.2 Single Master/Slave configuration (Ex applications)
For Ex instruments the termination resistor has to be inside the pressure tight section of the
housing. A terminating resistor is already supplied on the RS 485 module and only needs to
be enabled by soldering the two solder pads together (Fig. 2) or enabling the jumper which is
supplied on modules of a later design. (Fig. 3)
Fig. 2
Fig. 3
OFF Termination
RS 485
Module
S1
90
°
Pin header
Shorting link
ON Termination
Solder pads to
be joined
RS 485
Module