Overview
Section 4-1
59
Special I/O Unit Area and
Special I/O Unit DM Area
The Special I/O Unit Area and the Special I/O Unit DM Area are reserved for the
Unit according to the Machine Number (=N) set. For the Special I/O Unit Area 34
CIO words are allocated and for the Special I/O Unit DM Area 90 DM words are
allocated. For more information on the exact memory location of the Special I/O
Unit and Special I/O Unit DM Areas and the Machine Numbers that can be set,
refer to section
.
Unit Status Data
The Special I/O Unit Area contains the status information of the Counter Unit in
CIO and is divided in an area with output words and an area with input words. Both
areas are divided in three parts: a general part and two Counter specific parts, and
these are updated cyclically every I/O refresh.
Unit Configuration Data
The Unit configuration data is located in the Special I/O Unit DM Area, which is
allocated to the Counter Unit, and the Range/Comparison Data. The Mode for
which the Unit is configured determines if you have to set Range or Comparison
Data (refer to section 3-5-1
for more
information). The location of the Range/Comparison Data is indicated by an Indi-
rect Address that you have to specify for every Counter (refer to section 4-2-2
for detailed information).
The Special I/O Unit DM Area contains the configuration settings of the Counter
Unit. It is divided in three parts: a general part and two Counter specific parts. The
general part contains the settings that are relevant for the whole Unit and the
Counter specific parts contain the settings that are relevant to the specific
Counters.
The Unit Configuration Data is transferred to the Counter Unit at Power Up or after
the Unit has been restarted (refer to section 4-1-2
"Special I/O Units Restart bits"
).
Note
• The Unit configuration data can also be transferred during actual operation of
the Unit, by issuing an IOWR-instruction (refer to section 4-5-3-3
• I/O Refresh will not occur while the Data Transfer Busy bit (CIO n+17, bit 02)
is ON. For example, the Counter Value will not be refreshed while the bit is
ON.
