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each repeater) up to 247 on the same 4 wires. Using the RS-485 network, it is possible to read
each detector's status (fault, alarm) and to initiate a BIT to each detector individually.
The detector communicates via RS-485 with a Modbus RTU compatible protocol. For more
details on the communication protocol, please see manual F100P0013
2.11 Cabling Recommendations
The cable used should be appropriate for the hazardous area classification and meet local,
national and company regulations.
To comply with EMC regulations, the cable must be shielded, and the detector grounded.
The use of industrial-grade, suitably armoured field cable is recommended). When using HART®
communications, there are some additional considerations. In particular, a low capacitance
cable should be used. Further detailed information can be found at the HART® Communication
Foundation's website www.hartcomm.org .
2.12 Earth/Ground Regime
Any earthing regime employed must avoid earth loops. The following information is provided to
assist with proper earthing of the detector
•
There is an earthing point on the outside of the detector enclosure for connection to
Electrical ground
2.12.1 General recommendations
In general, correctly engineered star earthing arrangements minimize earth current
•
crosstalk and noise, improving the reliability and performance of instrumentation.
For more information & Technical support:
F-Guard UV-IR User Manual
Figure 20: RS-485 Networking
info@gastech.com
and
support@fg-detection.com
Doc. No. F110V0020.06
20
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