Extrel MAX300-RTG - Page 45

MAX300-RTG: Installation Manual Hardware Installation
45
The Modbus interface connections are accomplished by connecting to the terminal
block inside the external communications box. The Modbus protocol supports RTU
(remote terminal unit) transmission mode. This serial connection comes from the
designated serial port or the server PC.
Table 4: Modbus Serial Connection
Pin
RS232
RS422/RS485
4 wire:
internal
wiring
RS422/RS485
4 wire:
Customers
connection
RS485
2 wire:
internal
wiring
RS485
2 wire:
Customers
connection
1
2
RX
RD(A)-
TD(A)-
RX
TX
3
TX
TD(B)+
RD(B)+
TX
RX
4
RXA-
GND
GND
GND
GND
5
6
GND
GND
GND
GND
7
RD(B)+
TD(B)+
8
TD(A)-
RD(A)-
9
10
Not used
Not used
Not Used
Table 5: Modbus Serial Connection Switch
Switch
RS232
RS422
(4 wire)
RS485
(4 wire)
RS-485
(2 wire)
1
-
RS422
RS485
RS485
2
-
Echo ON
Echo ON
Echo ON
3
-
4 wire
4 wire
2 wire
4
-
4 wire
4 wire
2 wire
4-20mA and Digital I/O
The MAX300-RTG can be equipped with a Fieldbus I/O system capable of
accepting a variety of modules that communicate with external devices. These
modules and Bus coupler are mounted on a DIN rail located behind the access
door. Some possible I/O options include: