1 This International Standard specifies galvanic isolation of balanced interchange circuits using optocoupler integrated circuit technology and is provided for data transmission in the two-condition code (e.g. NRZ).
The electrical characteristics are compatible With both ISO 8482 and CCITT Recommendation V.11.
NOTE — Compatible means to allow interoperation with devices having interchange circuits conforming to the electrical characteristics specified in the referenced standards.
Annex A shows interoperation with CCITT Recommendation V. 11 interchange circuits in a point-to-point environment.
2 The specifications are given in terms of parameters and measurements for an isolated generator and an isolated receiver. These components may be used in twisted pair 2-wire or 4-wire point-to-point connections up to 1 000 m or multipoint connections up to 500 m for speeds up to 2 Mbit/s for point-to-point connections and 1 Mbit/s for multipoint connections. For data signalling rates up to 20 kbit/s, device manufacturers may optimize their component design.
3 Options are provided to meet special application requirements, such as
- isolated generator high impedance control;
- isolated receiver circuit failure detection capability;
- line termination in point-to-point configuration.
4 This International Standard does not describe a complete equipment interface in terms of mechanical, electrical and functional /procedural specifications.
DS/ISO/IEC 9549:1991 history
1991DS/ISO/IEC 9549:1991 Information technology. Galvanic isolation of balanced interchange circuits