Addressable Gas Detection System Manual
Addressable System Manual
11
Issue 2, January 2015
Dip-switches from 4 to 7: not used
Dip-switch 8: restore default settings
Position
Function
ON
When turned on, restores unit default settings
OFF
Normal position
2.2)
Field device connections
The unit comes complete with two RS485 bus lines (upgradeable up to 4) to which
gas detectors are connected. Serial buses are all open types.
On the same bus lines, it is possible to connect also addressable output modules.
The length of each serial bus line should not exceed 1,000 metres.
4 conductors are required for device connection (meaning both detectors and IN and
OUT modules): 2 for the RS485 serial bus and 2 for device power. For this reason
we suggest you use two different wires or a single wire with suitable features as
described below.
The RS485 serial bus must be connected with an EIA RS 485 connection wire: No. 2
conductors with 0.22/0.35 mm
2
s shield (TWISTED PAIR). Nominal capacity
between conductors < 50 pF/m, nominal impedance 120 ohm. Total line length with
this type of connection must not exceed 1000 metres. An example of a
recommended wire is a BELDEN 9841 or similar wire (EIA RS485 data transmission
wire). Only connect detectors (and IN and OUT modules) in cascade. Avoid tree or
delta connection since they reduce interference immunity.
Detector power supply (and IN and OUT modules on the bus) must be connected
with a 2-core wire with adequate section based on the number of connected devices,
their distance from the power supply and each device’s consumption (please see the
technical manual enclosed with gas detectors for this purpose).
Hydra
256
can support a maximum of 256 gas detectors. Gas detectors can be divided
on the bus lines provided that the maximum number of 64 detectors is not exceeded
on each bus line.
Each device connected to the RS485 buses must have a univocal address. See the
table on page 20 for output module address setting. For gas detectors, see the
technical manuals for address setting.
The table below lists the possible addresses for the various modules and detectors
connected to RS485 buses.
Module type
Available addresses
Notes
Bus
1
Bus
2
Bus 3
(optional)
Bus 4
(optional)
STG/OUT16-N
1-3
1-3
1-3
1-3
Up to a maximum of 3 modules in the
system.
STG/OUT16-S
1-
255
1-
255
1-255
1-255
Up to a maximum of 8 modules per line
and up to 16 maximum in the system.
Hydra+
Detectors
1-
128
1-
128
1-128
1-128
Up to a maximum of 64 detectors per line
and up to 247 maximum in the system.
