Eaton Electrical PROFIBUS-DP EZ204-DP - Manual (Page 97)

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7 EZ800/EZD Control Commands
Data exchange procedure The Control commands 9 bytes module allows extended data
exchange of the EZ800 and the EZD on the PROFIBUS-DP
communication bus. This allows you to transfer services from
the following areas:
• Read/write date and time (Page 95)
• Read/write image data (Page 99) and
• Read/write function block data (Page 120).
A data exchange procedure is required in order to ensure the
safe exchange of data via PROFIBUS-DP from master to
slave and vice versa.
Requirement:
The “Control commands 9 byte” module must have been
selected.
The master initiates the data exchange of the control
commands and the addressed slave responds.
During communication 9 data bytes (byte 0 = toggle byte,
bytes 1 to 8 information bytes) are sent via PROFIBUS.
The basic telegram structure is shown in the following
diagram.
Attention!
While a control command is being executed, the input and
output data will remain in the state before the control
command was called. Only after the “Control commands”
data exchange has been completed, will the I/O data be
refreshed.
Caution!
Only those values specified for the command code should
be used.
Check the values that you write in order to avoid
malfunctions.