BS 7404-3:1991

Committees responsible
National foreword
Specification
1. Scope
2. Object
3. Types of information
4. Interface between telecontrol equipment and process
     equipment
5. Interface between telecontrol equipment and
     operator's equipment
6. Interfaces between telecontrol equipment and
     communication subsystems
7. Interface between telecontrol equipment and other
     data processing equipment
Annex
ZA. Other international publications quoted in this
     standard with the references of the relevant
     European publications (normative)
Tables
1. Examples of relationships between signals and types
     of information
2. Nominal voltages for binary signals
3. Current classes for binary input signals
4. Current classes for binary output signals
5. Nominal values for analog signals
6. Interference voltage limits and insulation
     requirements for binary signals
7. Interference voltage limits and insulation
     requirements for analog signals
8. Active binary input signals
9. Passive binary input signals
10. Passive binary output signals
11. Active binary output signals
12. Analog input and output signals
13. Relationship between physical distance (DCE/DTE)
     and maximum transmission speed
14. CCITT, ISO and EIA recommendations/standards for
     CDE-DTE interfaces
Figures
1. Interfaces between modules in a typical telecontrol
     system
2. Level ranges of binary signals
3. Parameters of a binary signal
4. Level ranges of analog signals
5. Binary input circuits:
5a. Active binary input circuit
5b. Passive binary input circuit
6. Binary output circuits:
6a. Passive binary output circuit
6b. Active binary output circuit
7. Analog input and output circuits:
7a. Analog input circuit
7b. Analog output circuit

Defines electrical interface characteristics, e.g. signals, impedances, etc. which have to be met at the shared boundaries.

This series of standards applies to telecontrol equipment and systems with coded bit serial data transmission for monitoring and controlling geographically widespread processes.