TransCore encompass 4, Руководство пользователя

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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