TransCore encompass 4 - Table 4 Recommended Cable Length from Transformer to the Encompass 4 Reader; Table 5 Communications Interfaces and Conductor Requirements

Table 4 Recommended Cable Length from Transformer to the Encompass 4 Reader
Cable Size (AWG)
a
24 22 20 18 16 14 12
Maximum DCR (Ohms
per foot at 68°F)
b
0.0270 0.0175 0.0109 0.0069 0.0044 0.0027 0.0017
TransCore 5-ft cable
(P/N 58-1620-001)
c
23 ft 36 ft 58 ft 92 ft 144 ft 235 ft 373 ft
TransCore 20-ft cable
(P/N 58-1620-002)
c
15 ft 23 ft 38 ft 60 ft 93 ft 152 ft 242 ft
TransCore 35-ft cable
(P/N 58-1620-006)
c
7 ft 11 ft 17 ft 27 ft 43 ft 70 ft 110 ft
TransCore 45-ft cable
(P/N 58-1620-007)
c
1 ft 2 ft 4 ft 6 ft 9 ft 14 ft 23 ft
a Use two pair (two conductors for power and two for return). TransCore cable is 22AWG.
b Direct current resistance (DCR) information is from the Belden catalog.
c Based on a 1.0V drop at 1200 mA (RF ON) with 15% margin.
Host Communications
Your site design must include communications between the Encompass 4 Reader and a host computer. The
Encompass 4 Reader communicates with the host computer through an asynchronous serial line or through
a Wiegand interface. This serial line can be an RS–232 interface or an RS–422 interface. The host computer
must be able to accept one of the interfaces shown in Table 5.
Table 5 Communications Interfaces and Conductor Requirements 
Interface
Number of
Conductors
RS–232 3
RS–232 with RTS and CTS hardware and handshake signals 5
RS–422 5
Wiegand 3
RS–232 Interface
Use an RS–232 interface if one or more of the following conditions apply to your site:
• The host computer system is 50 ft (15.2 m) or less from the Encompass 4 Reader.
• The host computer system is more than 50 ft (15.2 m) from the Encompass 4 Reader and a pair of
RF modems or limited distance modem/line drivers over copper wire are used for communications
between the Encompass 4 Reader and the host. The distance from the RF modem to the
Encompass 4 Reader should not exceed 50 ft (15.2 m).
• Other common communications devices that can extend the RS–232 distance, such as fiber optic
modems, have been selected.
Chapter 2 Developing the Site Plan
TransCore Proprietary
2–17