6 Message Communications
6-16
CJ-series PROFIBUS Master Unit Operation Manual for NJ-series CPU Unit (W509)
Function code (Command, Response)
The function code is defined by the PROFIBUS standard and defines the type of MSAC1 message.
In the command it must be fixed to 005E (Hex). The response will contain either 005E (Hex) indicat-
ing a normal PROFIBUS completion, or 00DE (Hex), indicating PROFIBUS errors.
Slot number (Command)
The parameter Slot_Number is used in the destination device for addressing the desired data slot
(typically an I/O module). The number ranges from 0 to 254.
Index number (Command)
The parameter Index is used in the destination device for addressing the desired data block within a
specified slot. The number ranges from 0 to 254.
Data length (Bytes) (Command)
The Data length indicates the number of bytes, which have to be read. If the actual data block length
is less than requested, the length in the response will be the actual length of the data block. If the
actual data block length is greater or equal than requested, the response will contain the requested
length of data. The number ranges from 0 to 240.
Data (Response)
Requested data block as retrieved from the PROFIBUS DP-V1 slave device.
Error decode (Response)
The Error decode byte defines the type of errors reported in the Error code 1 and Error code 2, e.g.
a PROFIBUS DP-V1 error.This response will only be returned if the message was delivered suc-
cessfully, but the PROFIBUS service returned an error. Refer to A-7-4 PROFIBUS DP-V1 Error
Codes for more information.
Error code 1, Error code 2 (Response)
The contents of the Error code bytes depends on the contents of the Error decode byte and the
slave device.
The Error codes returned by a PROFIBUS DP-V1 slave device are defined in the PROFIBUS DP-V1
Extension to the PROFIBUS standard. This section lists the Error codes, which can be returned as a
result of a PROFIBUS DP-V1 MSAC1 services. From these codes, the user can determine the
cause of the failure.
The figure below shows the two of the three Error code bytes, returned by a PROFIBUS DP-V1
slave device, in case an MSAC1 service resulted in an error. The third byte, Error code 2, which is
not shown below will always contain user specific error codes.
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