Operating instructions

WirelessHART Fieldgate SWG70 5 Electrical Installation
Endress+Hauser 23
5.4 Connecting to RS-485
Fieldgate SWG70 is equipped with a fully galvanic isolated RS-485 interface. A second RS-485
terminal block allows several gateways to be connected through a daisy chain.
A terminating resistor is required at each end of the RS-485 cable. If the RS-485 is not routed to
other devices (no daisy-chain connection), activate the terminating resistor integrated in the
fieldgate.
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 1200m (at reduced communication speed).
• Use shielded twisted pair (STP) cables only.
• If the cable shield is grounded, the grounding should only be connected to one end of the cable,
in order to avoid equipotential bonding currents.
• Tension relief and bending radii: Ensure sufficient relief of tension on the cables during
installation and note the minimum bending radii of the cables.
Fig. 5-4: RS-485 interface
Connecting to RS-485 1 Check that the power is switched off
2 If applicable, unscrew the four screws of the housing cover (see Fig. 4-5 in Chapter 4.2) and
remove the housing cover.
3 Route the RS-485 cable through the first cable gland from left
– The permissible cable diameter lies between 6 mm and 10 mm.
4 Connect the RS-485 cable to the left terminal block labelled "RS485" (see Figure 5-4) as
follows:
5 For a daisy-chain connection, route the second RS-485 cable through the second cable gland
from left and connect it to the right terminal block labelled "RS485", see table above.
6 To activate the RS-485 termination, set DIP switch number 7 to "ON" (see Chapter 6.1.3).
7 Screw the housing cover to the housing again.
8 Tighten the cable gland with appropriate torque, see Chapter 5.5.
1 First RS-485 connection 2 Second RS-485 connection for daisy chaining
KL1 KL2 KL3 KL4
+24V +24V0V 0V
LINE1 LINE2
A
B
SHD
RS485
T1
T2
RX–
RX+
TX–
TX+
ON
OFF
SHD
A
B
SHD
RS485
ETHERNET
KL5 KL6
A B SHD
RS485
A B SHD
RS485
1
2
Wire RS-485 cable Fieldgate terminal Remarks
RxD/TxD– (RS-485 A) A RS-485 differential
signal
RxD/TxD+ (RS-485 B) B
Shield SHD Cable shielding