EM500 Open-Loop Vector Control Inverter User Manual
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(unavailable to be modified during inverter running), i.e., user may only operate the
parameters of “●” property (available to be modified during inverter running). If user
tries to modify the “○” property, an error code 1 will be returned.
12.3.3.4 0x08 Diagnosis function code
Function code 08 of Modbus offers a series of tests for checking the communication
system between client end (master) and server (slave) or checking various internal error
statuses in the server.
This function uses 2-byte sub-function code field in the inquiry to define the
executed test type. The servo will copy function code and sub-function code in normal
response. Some diagnoses can cause a remote device to return corresponding data
through the normal response data field.
Generally, sending diagnosis function command to a remote device will not affect
the user program in remote device. The diagnosis function can not have access to user
logic, for example discrete magnitude and register. Some functions can be used to reset
the error counter in the resent device.
The diagnosis function of our products is mainly line diagnosis (0000) and used for
testing normal communication of master and slaves. The normal response to the inquiry
data request should be returning the same data and copying the function code and the
sub-function code.
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