GE Hydran 201i, Инструкция по эксплуатации

Страница: 179 / 300

Communications in a Network, Using an RS-485 Local Network Link
Part 17997 Rev. 6, March 2011 9-3
Table 9-1 - Alarm Relay States, and Status of the H201T
i
, TDM Signal and H201C
i
-1
9.2 COMMUNICATIONS IN A NETWORK, USING AN RS-485 LOCAL
NETWORK LINK
Up to 128 Hydran 201T i Intelligent Transmitters can be connected in a single network to
be monitored and controlled by computer. Once the H201T i ’s are connected to a
Hydran 201C i -C or Hydran 201C i -1 Controller via an isolated supervisory link, each
Hydran 201C i Controller is linked to the next H201C i in a daisy-chain configuration via an
isolated RS-485 LAN. An example of local network is shown in Figure 9-1 on page 9-4.
Any H201C i in the network can then be linked to the host computer (see Section 9.3 on
page 9-5). Each H201T i can communicate with the host computer because each H201T i is
identified by a specific address (a number from 1 to 254) set by the user.
Note the following points:
• The total length of all RS-485 link cables in a single network must not exceed 1,200 m
(4,000 ft). This corresponds to an average length of 40 m (120 ft) for a local network
containing 32 H201C
i ’s.
• The RS-485 LAN uses an isolated, three-wire, shielded cable which is protected to
withstand the large noise transients typically found in electrical substations.
Alarm
a
Hydran 201T
i
a
a. — = Without consequence; H = High alarm; HH = High-High alarm; Sup. = Supervisory
Sup.
Link
a
TDM
a
Signal
Hydran 201C
i
-1
a
ac
Power
Relays
ac
Power
Relays
ppm
Display
Fail
b
b. On = Normal (no alarm); Off = Alarm
H HH Fail
b
H HH
None OK On Off Off OK Normal OK On Off Off On
H OK On On Off OK H OK On On Off On
HH OK On — On OK HH OK On On On On
Fail OK Off — — OK Fail OK Off Off Off Off
— — — — — Broken Fail OK Off Off Off Off
— — — — — — — Out Off Off Off Off
— Out Off Off Off — — — Off Off Off Off