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18 E2 MODBUS Network Wiring
• Connect the MODBUS Network to the RS485 Connector on the E2 PIB board (Belden 8641 recommended).
• Note to wire the RS485 +/- polarity at the E2 in the reverse of the XM670 - XM679 devices.
• Position the three termination jumpers to the UP (terminated) position to provide RS485 termination at the E2.
• Do not connect the shield of the MODBUS network to the E2 PIB center terminal. Instead, use a 100 ohm 1/2 watt
resistor to connect the MODBUS cable shield to earth ground.
• At each XM670 - XM679 device, wire the MODBUS cable to the RS485 +/- terminals and connect the MODBUS
shield to the pin 38 terminal.
• Terminate the end of the MODBUS network at the last XM670 - XM679 device on the daisy chain with the
MODBUS termination block (P/N 535-2711), or by connecting a 150 ohm resistor between the MODBUS +/-
terminals.
18 17
16 15 14 13
12
11
10 9
XM67XK Series
19 20
21
22 23 24 25 26
27
28
29
30
MODBUS TERMINATION
BLOCK 537-2711
150 ohm
Figure 18-1 - XM670 - XM679 to E2 MODBUS Network Wiring
CAUTION! For the XR, XM, and XEV series of controllers, the shield wire must not come into contact with
any other wire or ground source. If contact with other wires or devices does occur, the 485 MODBUS
network will malfunction or connected devices will be damaged. This applies to all installations where the
shield is tied to ground through a 100 ohm ½ Watt resistor.
Refer to Appendix A - Alternate MODBUS COM
Wiring Method for E2, XR, XM, and XEV Devices.
(Technical Bulletin P/N 026-4148.)
XM679 - 24VAC Valves/Wiring Diagram
8
7
3
2
1
18 17
16 15 14 13
12
11
10 9
XM67X Series
modbus
RS485
-
+
+
36
37
31
32
33
34
35
38
39
19 20
21
22 23 24 25 26
27
28
29
30
BELDEN 8641
(TYPICAL)
MODBUS 485
E2 STANDARD (3.XX and Below Version)
RS-232
POWER INTERFACE BOARD (PIB)
TERMINATE NETWORK
Position the three
jumpers to provide
RS485 termination
637-4890
at the E2
RX1
TX1
RX2
RS485-2A
+ 0V -
RS485-2B
+ 0V -
RS485-1B
Echelon Terminate Up
+ 0v -
+ 0v -
ON
EARTH GROUND
LON
Shield
LON
OFF
100 ohm
Watt
1/2
9600 Baud Only
8
7
3
2
1
18 17
16 15 14 13
12
11
10 9
8
7
XM67X Series
modbus
RS485
-
+
+
36
37
31
32
33
34
35
38
39
19 20
21
22 23 24 25 26
27
28
29
30
31
32
MODBUS 485
*Note that for E2 Enhanced PIB
boards, the RS-485 connection
Keyboard
can be wired on COM 2, COM 4,
or COM 6 port.
24VAC
AC1
AC2
earth ground
connection
BELDEN 8641
(TYPICAL)
3
2
1
modbus
RS485
-
+
+
36
37
33
34
35
38
39
REVERSE POLARITY OF +/-
ON RS485 CABLE FROM E2
E2 MODBUS Network Wiring • 31
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