Extended signaling protocol for alarm processes
The serial interface ESPA 4.4.4 is one of the ESPA ( E uropean S elective P aging Manufacturer's A ssociation) defined communications protocol for controlling Personenruffunkanlagen and telephone systems .
General
The protocol has developed as an industrial standard for the intercommunication of various systems, among other things for alarming and alarm communication, as well as for short messages between fire alarm systems, alarm servers, nurse call systems , building management systems , SCADA / PLC systems, telephone systems, DECT telephones or another device and a Vor -Replace site paging system. It was published in November 1984 in the publication ESPA 4.4.4 "Proposal for Serial Data Interface For Paging Equipment", hence the name of the protocol. Despite its age, it is still widely used in hospitals , nursing homes, and in corporate emergency systems.
construction
The protocol is message-oriented and based on short messages that are sent over a serial data link. It conforms to the ISO 1745 specification "Information Processing - Basic mode control procedures for data communication systems". It uses conventional stop-start character formats, a "handshake" protocol with error detection and is suitable for half-duplex operation. The data communication uses a serial, bit-synchronous character asynchronous format, as it is defined according to ISO 1177, whereby a start bit, seven information bits, an even parity bit and two stop bits are used. The international alphabet number 5 (CCITT V3 & ISO 646 ) is used as the character set.
It is suitable for multipoint connections ( RS-485 ) as well as for point-to-point connections ( RS-422 or RS-232 ). In the following, the term bus is used, even if there is only a point-to-point connection (bus with 2 participants).
functionality
Communication is based on the master / slave principle, so there is always a master unit and one or more slave units, whereby several slave units are only supported if the underlying data connection also includes several devices (e.g. Multi -Drop Bus), such as with RS-485. A slave unit cannot send data until it has been approved by the master. The master unit queries ( polling ) regularly slave units for new data. If a slave unit has data to send, it becomes the temporary master unit, takes control of the data connection and sends the data. Then control is returned to the master unit. Since there can be more than one slave unit, each device has an address, the master unit uses address 1, the first slave unit usually uses address 2.
ESPA-X
ESPA-X is a proprietary successor to the ESPA 4.4.4 protocol. ESPA-X is E rweitertes S ignalisierungs- P rotocol for A larmprozesse - X ML-based or e nhanced S ignaling P rotocol for A larm Processes - X ML-based and is based on TCP / IP and XML . It was developed in cooperation with the ESPA-X community and under the leadership of Unify and Tetronik . The ESPA-X Community today consists of 60 participating organizations, the majority of which are based in Europe (as of February 26, 2017).
Advantage compared to ESPA 4.4.4:
+ Use of IP, no restrictions on serial cable lengths
+ More messages at the same time
+ Time stamp for messages, assignment of repetitions or new, identical messages better
(Possibility of replying to past reports)
Disadvantage compared to ESPA 4.4.4:
- more complex structure of the data package [error analysis more difficult]
- Manufacturer-dependent use of fields and their content in the XML datagram
- Connection transmission and establishment, receiver is TCP / IP server mode [listening],
- Protocol specification not publicly available.
makes redundant transmission impossible!
European Selective Paging Manufacturers Association
The European Selective Paging Manufacturers Association , based in Eindhoven , Netherlands , was founded in 1972 by the then leading manufacturers of paging systems with the aim of standardizing regulations and technical specifications throughout Western Europe. The founding members were AEG Telefunken , Autophon , Hasler, Multitone, NIRA, Philips , Svenska Radio AB and Telekontroll AB.
The organization was later renamed European manufacturers of pocket communications systems . She also played a part in the development of the DECT standard.
Web links
Individual evidence
- ^ Proposal For Serial Data Interface For Paging Equipment . In: European Selective Paging Manufacturer Association (Ed.): ESPA . No. 4.4.4 , November 1984 ( osca-uk.com [PDF; 1.1 MB ; accessed on February 23, 2017]).
- ↑ Heiko Trapp: ESPA-X.org. In: ESPA-X.org. tetronik GmbH, accessed on February 26, 2017 .
- ^ Heiko Trapp: Member Directory. (No longer available online.) In: ESPA-X.org. tetronik GmbH, archived from the original on February 26, 2017 ; accessed on February 26, 2017 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Announcements . Electronics, television, radio, audio. In: Gordon Henderson (Ed.): Wireless World . Volume 79, No. 1448 . IPC Business Press Ltd, London February 1973, p. 89 (English).
- ↑ Diane Trivett: Cordless Telecommunications Worldwide: The Evolution of Unlicensed PCS . Ed .: Walter HW Tuttlebee. 1st edition. Springer-Verlag, London 1997, ISBN 978-1-4471-0913-6 , pp. 157 f ., doi : 10.1007 / 978-1-4471-0913-6 (English, books.google.com [accessed on February 24, 2017]).
- ↑ Wally HW Tuttlebee: Cordless Telecommunications in Europe: The Evolution of Personal Communications . Ed .: Wally HW Tuttlebee. 1st edition. Springer-Verlag, London 1990, ISBN 978-1-4471-3262-2 , Proprietary Digital Cordless Products, pp. 28 , doi : 10.1007 / 978-1-4471-3262-2 (English, books.google.com [accessed February 24, 2017]).
