IEC 62056-21:2002 pdf download
IEC 62056-21:2002 pdf download.Electricity metering – Data exchange for meter reading,tariff and load control – Part 21: Direct local data exchange.
4.3.5.4 Environmental lighting condition
The optical path (data transmission) shall not be affected by surrounding light with an intensity of up to 16 000 lux (light composition comparable with daylight, including fluorescent light).
4.3.5.5 Environmental temperature condition
The reference temperature is 23 °C ± 2 °C.
5 Character transmission
5.1 Type of transmission
Asynchronous serial bit (Start — Stop) transmission according to ISO/IEC 1177:1985, half-duplex.
5.2 Transmission speed
Initial baud rate — 300
Standard baud rates — 300, 600, 1 200, 2 400, 4 800, 9 600, 19 200
Special baud rate — as desired.
NOTE The maximum speed may be limited by the reading head or the optical port or the ITU-T Recommendation V.28 limitations in the tariff device.
5.3 Signal quality According to ISO/IEC 7480:1991:
— category I for the transmitter; category A for the receiver.
5.4 Character format
Character format according to ISO/IEC 1177:1985.
(1 start bit, 7 data bits, 1 parity bit, 1 stop bit).
NOTE Protocol mode E (see 6.4.5) may use byte transparency, 1 start bit, 8 data bits, 1 stop bit (e.g. see Annex E).
5.5 Character code
Character code according to ISO/IEC 646:1991, international reference version. For local use, a national replacement code can be used.
NOTE Protocol mode E (see 6.4.5) may use byte transparency.
5.6 Character security
With parity bit, even parity according to ISO/IEC 1177:1985.
NOTE Protocol mode E (see 6.4.5) may use byte transparency, specific security may be used.
6 Data transmission protocol
6.1 General
The protocol offers five alternative protocol modes, which can be used by the tariff device: A, B, C, D and E. Mode selection is a subset of ISO/lEG 1745, basic mode control procedures.
Data exchange is bi-directional in protocol modes A, B, C and E and is always initiated by the HHU with a transmission of a request message. In protocol modes A to C, the HHU acts as a master and the tariff device acts as a slave. In protocol mode E, the HHU acts as a client and the tariff device acts as a server. These protocol modes permit meter reading and programming. Protocol mode E may be a transparent binary mode.
Data exchange is unidirectional in protocol mode D and permits readout only. The information flows from the tariff device to the HHU. Data transmission is initiated, for example by operating a push button or other sensor on the tariff device.
The protocol mode used by the tariff device is indicated to the HHU by the identification message. Protocol modes A to D are identified by the baud rate identification character (see item 13 in 6.3.3) while protocol mode E is identified by an escape sequence (see items 23 and 24 in 6.3.2). Protocol mode E enables to use various protocols, one of them being the METERING HDLC protocol as described in Annex E.
6.2 Calculation of the block check character
The readout of data may be performed without block check character. Whenever used, the block check character shall comply with ISO/IEC 1155:1978.
6.3.14 Explanations of message contents
1) Start character “I” (forward oblique, code 2FH).
2) End character “!“ (exclamation mark, code 21 H).
3) Completion character (CR, carriage return, code ODH; LF, line feed, code OAH).
4) Acknowledge character (ACK, acknowledge, code 06H).
5) Frame start character (STX, start of text code 02H) indicating where the calculation of BCC shall start from. This character is not required if there is no data set to follow.
6) End character in the block (ETX, end of text, code 03H).
7) End character in a partial block (ECT, end of text block, code 04H).
8) Block check character (BCC), if required, in accordance with the characters 5) and 6). Items 5) and 6) do not apply when the data block is transmitted without check characters.
9) Transmission request command (question mark, code 3FH)
10) Protocol control character (see 6.4.5.2).
11) Mode control character (see 6.4.5.3).
12) Manufacturer’s identification comprising three upper case letters except as noted below:
If a tariff device transmits the third letter in lower case, the minimum reaction time t,. for the device is 20 ms instead of 200 ms. Even though a tariff device transmits an upper case third letter, this does not preclude supporting a 20 ms reaction time.
These letters shall be registered with the administrator: The FLAG Association (see the foreword).
13) Baud rate identification (for baud rate changeover)
The request message, the identification message and the acknowledgement/option select message are transmitted at the initial rate of 300 Bd (except protocol mode D). The baud rate of the data message depends on the baud rate determined by the protocol.
a) Protocol mode A (without baud rate changeover)
Any desired printable characters except “I” and as long as they are not specified for protocol mode B or protocol mode C.
b) Protocol mode B (with baud rate changeover, without acknowledgement/option select message)
