HNC Electric HV610C Series, Руководство пользователя

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Appendix I H5RS485 Card & RS485Communication Protocol
126
In RTU mode, the message transmission must start with a pause interval of at least 3.5
characters. This is the easiest way to achieve various character times under the network baud
rate (as shown in T1-T2-T3-T4 in the figure below). The first field transmitted is the device
address. The transmission characters that can be used are hexadecimal 0...9, A...F. The
network device continuously detects the network bus, including the pause interval. When the
first field (address field) is received, each device decodes it to determine whether to send it to
itself. After the last transmitted character, a pause of at least 3.5 characters marks the end of the
message. A new message can start after this pause. The entire message frame must be
transmitted as a continuous stream. If there is a pause of more than 1.5 characters before the
frame is completed, the receiving device will refresh the incomplete message and assume that
the next byte is the address field of a new message. Similarly, if a new message starts after the
previous message in less than 3.5 characters, the receiving device will consider it a continuation
of the previous message. This will cause an error, because the value in the final CRC field
cannot be correct.
RTU frame format
：
START 3.5-character time
Slave address ADDR
Communication address
：
1~247
Command code CMD 03
：
Read slave parameters
；
06
：
Write slave parameters
DATA (N-1)
Function code parameter address,function code parameter
number,function code parameter value,etc.
DATA (N-2)
………………………
DATA0
CRC CHK low order
Detection value
：
CRC value
。
CRC CHK high order
END
At least 3.5-character time
CMD(command instructions) and DATA (material words description)
Command code
：
03H
，
reads words(There are12 characters can be read at most). For
example
：
the inverter start address F0.02 of the slave machine address 01 continuously
reads two consecutive values.
Host command
ADR 01H
CMD 03H
Start address highorder
F0H
Start address loworder
02H
Register number highorder
00H
Register number loworder
02H
CRC CHK low order
CRC CHK values to be calculated
CRC CHK high order
Slave response