Sensitron MULTISCAN 8+ - Field Device Connections; RS485 Bus Connection Principles

MT4221 Rev3
20/05/2020
44
Instruction Manual Multiscan 8+
ENGLISH
ON
OFF
38400 Bit/sec.
OFF
OFF
115200 Bit/sec. (default)
Dip-switches 6 and 7: not used
Table 8: Dip-switch 8: Configuration reset
Position
Function
ON
If set to ON, default data is restored when the central unit is switched on
OFF
Normal position
Table 9: SD3 Language setting
LANGUAGE
SW 1
SW2
SW3
SW4
English
OFF
OFF
OFF
ON
Italian
OFF
ON
ON
ON
Spanish
ON
OFF
ON
ON
Portuguese
OFF
OFF
ON
ON
German
ON
ON
OFF
ON
French
OFF
ON
OFF
ON
Slovenian
ON
OFF
OFF
OFF
2.2 Field device connections
The unit has 1 RS485 data bus to which 8 gas detectors can be connected.
The gas detectors are connected through the serial bus (directly in the serial RS485 if
equipped with serial output or through 1 module with 8 STG/IN8 S inputs if of type 4-20
mA) and the STG/OUT16-S output module.
The maximum length of each serial data bus is 800 m.
To connect devices, 4 conductors are required (intended both as detectors with a serial
output as well as IN and OUT modules): 2 for the RS485 serial bus and two for powering
the devices. For this reason, two different wires must be used or a single wire that has
suitable characteristics, as described below.
-) The RS485 serial bus must be connected with an EIA RS 485 connection wire: No. 2 wires
with 0.22/0.35 mm2 section with 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 metres. An example of a recommended cable is a
BELDEN 9841 or similar wire (EIA RS485 data transmission wire). Only connect detectors