Atlas Copco PowerMACS 4000, User Manual

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Peripheral Devices
500 9836 3521 01
The CMD word is laid out as follows:
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name R W F S X d2 d1 d0 - - - - - - - -
The respective bits have the following meaning:
Name Meaning Usage
R Read Set one (1) to read the process data selected with DataType.
W Write Set one (1) to write the process data selected with DataType.
F Flush Set one (1) to flush the data queue selected with DataType. Flushing will delete all
items in the specified process data queue. However, a data item currently being read
will not be deleted. It can safely be read also after that this command has been issued.
S Skip Set one (1) to skip reading of the current data item in the data queue selected with
DataType. Next reading will return next data item (or the first part of it) in the queue.
X Extended
format This bit is normally 0.
If this bit is set then which process data queue to read is not specified using the d2..d0.
Instead the queue is specified using an address following the CMD byte. See Using the
extended format for a detailed description. This can be used for to access more data to
the PLC then the particular fieldbus allows.
d2..d0 DataType Specifies which process data queue the command is issued for.
DataType = 4
d2
+ 2
d1
+ 1
d0
d. Allowed values of DataType are:

1: Cycle data queue

2: Event queue

3: Trace queue

4: Setup