INVT Goodrive GD300-19-004G-4, Руководство по эксплуатации

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Goodrive300-19 series open loop vector inverter special for hosit Communication protocol
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DATA (N-1)
…
DATA (0)
The data of 2*N bytes are the main content of the communication as
well as the core of data exchanging
CRC CHK low bit
Detection value: CRC (16BIT)
CRC CHK high bit
END T1-T2-T3-T4 (transmission time of 3.5 bytes)
10.3.2.2 RTU communication frame error checkout
Various factors may cause errors in the data transmission. If there is no error checkout, the receiving
devices will not find the message is wrong and they may give an incorrect response which may cause
serious impact. So the checkout is essential to the message.
The theme of checkout is that: the sender calculates the sending data according to a fixed formula,
and then sends the result with the message. When the receiver gets this message, it will calculate
anther result according to the same method and compare it with the sending one. If two results are
the same, the message is correct. If not, the message is incorrect.
The error checkout of the frame can be divided into two parts: the bit checkout of the byte and the
whole data checkout of the frame (CRC check).
Bit checkout of the byte
The user can select different bit checkouts or non-checkout, which impacts the check bit setting of
each byte.
The definition of even checkout: add an even check bit before the data transmission to illustrate the
number of
“1” in the data transmission is odd number or even number. When it is even, the check byte
is
“0”, otherwise, the check byte is”1”. This method is used to stabilize the parity of the data.
The definition of odd checkout: add an odd check bit before the data transmission to illustrate the
number of
“1” in the data transmission is odd number or even number. When it is odd, the check byte
is
“0”, otherwise, the check byte is”1”. This method is used to stabilize the parity of the data.
For example, when transmitting
“11001110”, there are five “1” in the data. If the even checkout is
applied, the even check bit is
“1”; if the odd checkout is applied; the odd check bit is “0”. The even and
odd check bit is calculated on the check bit position of the frame. And the receiving devices also carry
out even and odd checkout. If the parity of the receiving data is different from the setting value, there
is an error in the communication.
CRC check (Cyclical Redundancy Check)
The checkout uses RTU frame format. The frame includes the frame error detection field which is
based on the CRC calculation method. The CRC field is two bytes, including 16 figure binary values.