Connecting To Rs-485 - Pepperl+Fuchs WHA-GW Manual

WHA-GW-*
Installation
3.4

Connecting to RS-485

Danger!
Explosion hazard in Zone 2 when operating powered Gateway
If the Gateway is installed in Zone 2 and connected to power, there is an explosion hazard
when operating DIP switches, buttons or connecting/disconnecting cables.
The operation of DIP switches/buttons and the connection/disconnection of any cables in
Zone 2 is only permitted in the absence of a hazardous atmosphere or if the device is
disconnected from power!
The Gateway is equipped with a fully galvanic isolated RS-485 interface. The interface is
daisy-chain capable through its duplicated RS-485 terminal block.
A terminating resistor is integrated and may be switched on/off by using the corresponding
DIP switch inside the Gateway housing (see chapter 6.1) . It is also possible to switch on/off
the terminating resistor via software (see chapter 5.5.1).
If the RS-485 cable ends at the WirelessHART Gateway and is not routed to other devices
(no daisy-chain connection), activate the terminating resistor to ensure reliable RS-485
communication.
Note!
Keep in mind the location of the Modbus PLC or DCS. The maximum length of the cable
running from the Gateway to the PLC/DCS is 1200 m (at reduced communication speed).
Use shielded twisted pair (STP) cables only.
Figure 3.11RS-485 interfaces
1 First RS-485 interface
2 Second RS-485 interface
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