
3-34
FMT 3000 Hardware Reference Guide - Option Installation and Operation
Figure 3-30. RS-485 Option Simplified Schematic and Custom Resistor Locations
R3
R2
R5
R1
R4
R1
TS1
B
A
GND
1
2
3
+ISO Vcc
ISO GND
B
A
R5
R2
R3
R4
Protection
Diodes
1.5K
1.5K
1.5K
1.5K
Pull Down Resistors R3 and R4 are not installed.
150
R1 to R5 are mounted in sockets
to facilitate user configuration.
Pull Up Resistors R1 and R2 are installed at the factory.
Isolation and
Interface Circuit
RTS
TX
RX
+Vcc
GND