These alarm systems are designed for the securing of small and middle sized properties. Nevertheless, it is sometimes necessary to extend their buses over optical fiber. This simple task provide two problems:
Extreme Sensitivity to Delay
The communication in the bus is based on synchronnous data transmission principle. At the delay of around 200µs, the communication with modules starts to break down. This disables the transmission of data over fiber optics in packets, just as TCP communication.
Non-Standardized Physical Interface
System buses of these alarm systems are four-wire:
- + supply
- - supply
- data (both directions)
- synchronization (one direction from the alarm system to modules)
The transmission itself is, compared to e.g. symmetric interface RS485, asymmetric with the 12V logic.
A very handy solution for the transmission of system buses are digital fiber optic converters. Why?
- Their delay of transmitted data is only 70µs
- They can be universally used for both MM SM fibers
- They don't need any setting of communication speed, parity, ...
- They are compatible with systems ABI, MB SECURE, PARADOX EVO, SATEL INTEGRA
Updated: 11. 03. 2020