ENGLISH
Pag. 43
The length of each serial data bus is maximum 1000 mt.
4 conductors are required for device connections: 2 for the RS485 serial bus and two for devi-
ce power. For this reason, two different wires must be used or a single wire that has suitable
characteristics, described below
³
The RS485 serial bus must be connected with an EIA RS 485 connection wire: No. 2
conductors with 0.22/0.35 mm2 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 1.000 meters. 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.
³
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 tech-
nical manual enclosed with gas detectors for this purpose).
The MU+/S1-32 can support a different number of detectors up to 32. Each device
connected on the unit’s RS485 bus must have its own univocal address. STG/IN8S and STG/
OUT16S module address settings are described later in this manual. See the manual of the
detector for its address settings.
2.8
Detectors’ connection
Gas detectors can be connected to the MU+/S1-32 control panel in two different
ways, based on the detector output signal.
1. 4-20 mA analogue proportional output
The detector connected to the unit and STG/IN8S modules will send a 4-20 mA signal refer-
ring to its range (i.e. 0-300 ppm, 0-30 ppm, 0-100% LEL etc.) and the unit, suitably program-
med, will display the relevant gas concentration indication measured by the detector and
consequently activate the alarms when the set values are reached.
2. RS485 digital proportional output
The detector connected to the unit will send a data signal on the RS485 line. This signal is
referring to its range (i.e. 0-300 ppm, 0-300 ppm, etc.) and the unit, suitably programmed,
will display the relevant gas concentration indication measured by the detector and conse-
quently activate the alarms when the set values are reached.
2.7
Field device connections
The unit has as default condition 1 RS485 data bus connected to field gas detectors. As op-
tion, 1 more serial line can be added.The serial buses can be used in “open” mode (2 bus) or
“closed” (1 bus). The choice is set during programming with the PC software.
Via serial bus the gas detectors are connected (directly via RS485 serial for models with this
communication or via the 8-input STG/IN8S modules if 4-20 mA type) and ST.G/OUT16-S
output modules.
Summary of Contents for MULTISCAN++/S1-32
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