INVT SV-DA200 Operation Manual page 232

SV-DA200 series AC servo drives
bit, the tailed and the odd and even check bit is ineffective.
During the generating CRC, each 8-bit is XOR with the register content, the result shifts toward the
min. effective bit while the max. effective bit is filled with 0. LSB is extracted for detection. If LSB is 1,
the register is XOR with the preset value independently, if LSB is 0, no action. The whole process will
be repeated 8 times. After the last bit (8
current value of register independently. Finally, the value in the register is the CRC value after all
bytes in the frame are executed.
The calculation of CRC applies the international standard CRC checkout principles. When the user is
editing CRC calculation, he can refer to the relative standard CRC calculation to write the required
CRC calculation program.
8.2.6 Fault Responses
The slave uses functional code fields and fault addresses to indicate it is a normal response or some
error occurs (named as objection response). For normal responses, the slave shows corresponding
function codes, digital address or sub-function codes as the response. For objection responses, the
slave returns a code which equals the normal code, but the first byte is logic 1.
Example: When the master sends a message to the slave, requiring it to read a group of address
data of servo device function codes, there will be following function codes:
For normal responses, the slave responds the same codes, while for objection responses, it will
return:
Besides the function codes modification for the objection fault, the slave will respond a byte of
abnormal code which defines the error reason.
When the master receives the response for the objection, in a typical processing, it will send the
message again or modify the corresponding order.
Code Name
01H Illegal function
Illegal data
02H
address
Illegal data
03H
value
11H Check error
th
bit) completes, the next 8-bit byte will be XOR with the
0 0 0 0 0 0 1 1 (Hex 03H)
1 0 0 0 0 0 1 1 (Hex 83H)
Table 8-6 Meaning of error code
Modbus abnormal code
Receiving function codes from the upper devices is not allowable. This
may because these function codes can only be applied to new devices
or the slave device is dealing with this requirement in a wrong situation.
For servo drives, the required data address is not allowed; especially the
mix of the register address and transmitting byte numbers is invalid.
The data value received is beyond the range of address parameters,
leading the parameter modification invalid.
In the frame message sent by the upper devices, if the CRC check bit of
RTU format or the LRC check bit of ASCII format is different from the
check number calculated by below devise, check error will be reported.
‐222‐
Meaning
Communication