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Rockwell Automation Publication ICSTT-RM448J-EN-P - April 2018
Chapter 5
Install the AADvance System
1
The line functions shown in the table ("receive" and "transmit") are with
respect to the processor base unit.
Connecting MODBUS Slave Devices to Serial Ports
You can use a full duplex or a half-duplex connection for a MODBUS Slave
device on a serial port.
Terminal
Function Description (4-wire)
1
Function Description (2-wire)
1
TRX_A
Receive data A (inverting)
Transmit/receive data A (inverting)
TRX_B
Receive data B (non-inverting)
Transmit/receive data B (non-inverting)
0V
Instrument ground (signal ground)
Instrument ground
TX_B
Transmit data B (non-inverting)
not used
TX_A
Transmit data A (inverting)
not used
NOTE
To connect to the external communication link you should
terminate the receive end of the twisted pairs with a 120 Ω
resistor in series with a 68nF capacitor at the receiver ends.
