Micom P721, Техническое руководство

Страница: 242 / 334

P72x/EN CT/A11 Communication database
Page 52/78 MiCOM P721/P723
5.3 Message validity check
The validation of a frame is performed with a 16-bit Cyclical Redundancy Check (CRC).
Generator polynomial: 1+x²+x
15
+x
16
= 1010 0000 0000 0001 (binary) = A001 (hexadecimal)
5.4 IEC870-5-103 address
A slave address is defined in the range 1-254.
The address “255” is a standard address, frames with 255 are received by all slave devices.
5.5 Initialisation
Whenever the relay has been powered up, or if the communication parameters have been
changed a reset command is required to initialise the communications. The relay will
respond to either of the two reset commands (Reset CU or Reset FCB), the difference being
that the Reset CU will clear any unsent messages in the relay’s transmit buffer.
The relay will respond to the reset command with an identification message ASDU 5, the
Cause Of Transmission COT of this response will be either Reset CU or Reset FCB
depending on the nature of the reset command. The following information will be contained
in the data section of this ASDU:
Manufacturer Name: Schneider Electric
The Software Identification Section will contain the first four characters of the relay model
number to identify the type of relay, e.g. P723.
In addition to the above identification message, if the relay has been powered up it will also
produce a power up event.
5.6 Time synchronisation
The relay time and date can be set using the time synchronisation feature of the IEC60870-
5-103 protocol. The relay will correct for the transmission delay as specified in IEC60870-5-
103. If the time synchronisation message is sent as a send/confirm message then the relay
will respond with a confirm. Whether the time synchronisation message is sent as a send
confirm or a broadcast (send/no reply) message, a time synchronisation message will be
returned as Class 1 data.
5.7 Spontaneous events
The events created by the relay will be passed using the standard function type/information
numbers to the IEC60870-5-103 master station. Private codes are not used, thus any events
that cannot be passed using the standardised messages will not be sent.
Events are categorised using the following information:
•
Common Address
•
Function Type
•
Information number
•
Cause of Transmission (to caracterise event origin).
APPENDIX 1 contains a complete listing of all events produced by the relay.
5.8 General interrogation
The GI request can be used to read the status of the relay, the function numbers, information
numbers and common address offsets that will be returned during the GI cycle are indicated
in APPENDIX 1.