Rs485 Serial Port - Weidmuller WI-GTWY-9 User Manual

WI-GTWY-9-xxx Wireless Gateway

RS485 Serial Port

RS485 should not be used with the DF1 unit. The RS485 port provides for communication
between the WI-GTWY-9-xxx unit and its host device using a multi-drop cable. Up to 32
devices may be connected in each multi-drop network. Note that the RS485 port is shared
internally with the RS232 port - make sure that the RS232 port is disconnected before using the
RS485 port.
WI-GTWY9
INTERNAL
RESISTOR
RS485 is a balanced, differential standard but it is recommended that shielded, twisted pair cable
be used to interconnect modules to reduce potential RFI. An RS485 network should be wired as
indicated in the diagram below and terminated at each end of the network with a 120-ohm
resistor. On-board 120 ohm resistors are provided and may be engaged by operating the single
DIP switch in the end plate next to the RS485 terminals. The DIP switch should be in the "1" or
"on" position to connect the resistor. If the module is not at one end of the RS485 cable, the
switch should be off.
It is important to maintain the polarity of the two RS485 wires. On the WI-GTWY-9-xxx,
terminal A (the terminal on the right) is positive and terminal B is negative.
EXTERNAL RESISTOR
REQUIRED
TERMINATING
RESISTOR SWITCH
ON = TERMINATION
OFF = NO TERM.
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