GE DGP Series, Инструкция по эксплуатации

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GE Power Management DGP Digital Generator Protection System 9-
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9 COMMUNICATIONS 9.3 MODBUS FUNCTIONS
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9.3 MODBUS FUNCTIONS 9.3.1 FUNCTION CODE 03/04: READING HOLDING/INPUT REGISTERS
a) DESCRIPTION
Reads the binary contents holding/input registers (actual values) in the slave. They can be set point registers
or any of the information reports, such as actual values.
b) QUERY
The query message specifies the starting register and the number of registers to be read.
c) RESPONSE
The register data in the response is packed as two bytes per register. For each register the first byte contains
the higher order byte and the second contains the lower order byte.
Example of typical response message
Field: Bytes Example (hex):
SLAVE ADDRESS 1 11 Message for slave 17
FUNCTION CODE 1 03/04 Read registers
Starting address 2 Starting address of the register. High byte first and then the Low Byte
Num points 2 Number of registers to read. High Byte first then Low byte
CRC 2 CRC Calculated by master. High byte first. Low byte next
Field: Bytes Example (hex):
SLAVE ADDRESS 1 11 Message from slave 17
FUNCTION CODE 1 03/04 Read registers
Byte Count 1 Number of registers to read.
Data 1 2 High Byte first then Low byte
......
Data n 2 High Byte first then Low byte
CRC 2 CRC calculated by slave. High byte first, Low byte next