Specifications

26 • XR35CX I&O Manual 026-1203 Rev 0 09-FEB-2011
18.2.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 XR35CX con-
trollers to E2, Belden #8641 (CPC 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:
18.3.MODBUS Termination
Blocks
Because the XR35CX 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 18, keep-
ing the exposed shield wire length as short as possible
(3 inches ideal maximum length).
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 18-8 - MODBUS Termination Block (P/N 535-2711)
SHIELD WIRE
(CONNECT TO
OF LAST DEVICE)
PIN 18
FROM OTHER
DEVICES
TO LAST DEVICE
AT END OF DAISY
CHAIN