Wiring Types ECT MODBUS Networking to E2s • 25
firmware on it.
19.4.Wiring Types
Retail Solutions specifies Belden #8761 shielded
twisted pair cables for use as MODBUS wiring (or
Belden #82761 and Belden #88761 for plenum instal-
lations).
For MODBUS network wiring of XEV series of
controllers to E2, Belden #8641 (P/N 135-8641) is the
recommended wire type to use.
If the recommended cable is not available in your
area, be sure the wiring meets or exceeds the follow-
ing specs:
The maximum distance between an XEV22 con-
troller and a valve must not exceed 10 meters (32
feet). Use only shielded cables with a cross section
greater than or equal to 0.325 mm
2
(AWG22).
19.5.MODBUS Termination
Blocks
Because the XEV22D device has no on-board
means of termination, use the MODBUS termination
block (P/N 535-2711) for termination that can be
wired to the end of the cable segment using the three-
pin connector. Wire the two signal wires to the out-
side terminals, and connect the shield to pin 16, keep-
ing the exposed shield wire length as short as possible
(3 inches ideal maximum length).
Figure 19-8 - Network Summary Screen
Shielded? Yes
Conductor Type Twisted Pair
Gauge 18 - 24 AWG
Capacitance between
signal wires
31 pF/ft or less
(9.45 m) or less
Capacitance between
signal and shield
59 pF/ft or less
(17.98 m) or less
Maximum Length 4000 ft/18 to 22 AWG
(1219.2 m)
2500 ft/24 AWG
(762 m)
Nominal Impedance 120±50
Figure 19-9 - MODBUS Termination Block (P/N 535-2711)
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