IM300 Intelligent Power Monitoring Instrument
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format:
Odd-even check:
Start bit(1)
Data bits(8)
Parity check
bit(1)
End bit(1)
0
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
1
No parity check:
Start bit(1)
Data bits(8)
End bit(1)
End bit(1)
0
0/1
0/1
0/1
0/1
0/1
0/1
0/1
0/1
1
1
4.1.2 The frame format
Data frame arrived at the terminal, The device removes the header of the data
frame, read the data and perform the required tasks if it is detected correctly, Then put
the generated data into the data frame and send it back to the requester. The returned
data frames include: terminal address, executed command, data, check code.
Address
Function
Data
Check
8-Bits
8-Bits
N×8-Bits
16-Bits
Address code:
The address code is the first byte of each communication frame, ranging from 0
~ 255 (00H ~ FFH). Each slave station must have a unique address code, and only the
one that conforms to the address code can respond and send back the message. When
the information is sent back from the slave station, the return data is started with their
respective address codes. The address code that is sent indicates the address that will
be sent from the slave station, and the address code returned from the slave station
indicates the return from the slave station address. The corresponding address code
indicates where the information came from. 00H is the broadcast address, all slave
substations respond to the broadcast command, but no information is returned.
Function code
：
The function code takes up a byte, range 1 ~ 127 (01H ~ 7FH), and tells the
terminal device to perform what operation. The function code used in the device is
shown in the following table:
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