XM679 - 24VAC Valves/Wiring Diagram
E2 MODBUS Network Wiring • 31
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 /-
terminals.
Refer to
Appendix A - Alternate MODBUS COM
Wiring Method for E2, XR, XM, and XEV Devices.
(Technical Bulletin P/N 026-4148.)
Figure 18-1 - XM670 - XM679 to E2 MODBUS Network Wiring
LON
EARTH GROUND
AC1
Shield
24VAC
Keyboard
RS-232
AC2
ON
OFF
LON
RS485-1B
+ 0v -
E2 STANDARD (3.XX and Below Version)
POWER INTERFACE BOARD (PIB)
237-
4810,
V
er
s
ion
1.
00
E
2
Po
w
e
r
In
te
rf
a
ce
Bo
a
rd
(P
.I
.B.
)
R
Echelon Terminate Up
+ 0V -
RS485-2B
TX1
RX2
RX1
JP4
JP
5
JP
6
JP
1
JP
2
JP
3
REVERSE POLARITY OF +/-
ON RS485 CABLE FROM E2
BELDEN 8641
(TYPICAL)
earth ground
connection
100 ohm
Watt
1/2
18 17 16 15 14 13
12
10 9
7
8
11
3
2
1
19 20
22 23 24 25 26
39
38
37
36
35
34
33
32
31
30
29
28
27
21
+
RS485
-
+
modbus
Bl
ac
k
Wh
ite
XM67X Series
S
h
ield
MODBUS TERMINATION
BLOCK 537-2711
150 ohm
18 17 16 15 14 13
12
10 9
7
8
11
3
2
1
19 20
22 23 24 25 26
39
38
37
36
35
34
33
32
31
30
29
28
27
21
+
18 17 16 15 14 13
12
10 9
7
8
11
3
2
1
19 20
22 23 24 25 26
39
38
37
36
35
34
33
32
31
30
29
28
27
21
+
RS485
-
+
modbus
Bl
ac
k
Wh
ite
RS485
-
+
modbus
Bla
ck
Wh
ite
BELDEN 8641
(TYPICAL)
Sh
ie
ld
Sh
ie
ld
XM67X Series
XM67XK Series
Position the three
jumpers to provide
RS485 termination
at the E2
TERMINATE NETWORK
+ 0v -
637-4890
Wh
it
e
+
Bl
ack
-
RS485-2A
+ 0V -
9600 Baud Only
*Note that for E2 Enhanced PIB
boards, the RS-485 connection
can be wired on COM 2, COM 4,
or COM 6 port.
MODBUS 485
MODBUS 485
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.
